Lubricating compositions having improved shear stability

ABSTRACT

A lubricating composition with improved shear stability having a kinematic viscosity (Kv 100 ) from 5 to 32.5 cSt at 100° C., and a viscosity index from 140 to 200. The lubricating composition includes: a bi-modal blend lubricating oil including from 20 to 99 weight percent of a low viscosity basestock having a Kv 100  from 2 to 8 cSt at 100° C., and from 1 to 20 weight percent of a high viscosity basestock having a Kv 100  from 40 to 600 cSt at 100° C.; a viscosity modifier including a copolymer having units derived from monomers of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol; and an alkylated aromatic co-base stock in an amount from 1 to 8 weight percent and having a Kv 100  from 3 to 15 cSt at 100° C.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser. No. 61/748,539 filed Jan. 3, 2013, herein incorporated by reference in its entirety.

FIELD

This disclosure relates to lubricating compositions containing a bi-modal blend lubricating oil, a viscosity modifier, and an alkylated aromatic co-base stock such as an alkylated naphthalene, that provide improved shear stability as measured by the KRL 20 hour Tapered Roller Bearing Test (CEC L-45-A-99), lubricants derived therefrom, processes for preparing same, and methods of use thereof. This disclosure relates to lubricating driveline devices, e.g., gears and transmissions, using the lubricants to improve fuel efficiency without sacrificing driveline device durability.

BACKGROUND

Environmental regulations are driving vehicle fuel economy standards and there is increased emphasis on and market demand for higher efficiency driveline fluids, particularly axle oils that can delivery fuel economy and maintain hardware protection capability. A proven approach to enhancing lubricant derived fuel efficiency is lower fluid viscosity. Since equipment durability cannot be compromised, equal or lower viscosity lubricants must deliver improved efficiency while retaining the same level of protection against various types of hardware damage (e.g., wear, micropitting, scuffing, scoring, and the like). Improved durability and reduced component wear increases equipment operating life and reduces maintenance costs and downtime. Improved shear stability is likewise desirable to provide enduring performance (i.e., oil film stability) throughout the useful life of the lubricant. Additionally, different transmission applications have specific friction requirements, some of which may benefit from higher friction.

In particular, the shear stability of lubricants is taking on greater importance as the use of wide-span multigrade lubricants increases. The use of multigrade lubricants helps improve fuel economy, assists in smoother shifting and has shown to extend lubricant service life. The ability of the lubricant to stay-in-grade is part of the SAE J306 standard. Depending on the viscosity grade, some lubricants typically contain high levels of polymer, which can shear in service. This shear reduces viscosity and decreases the lubricant's protective fluid film thereby increasing the potential for premature equipment failure. A lubricant that is formulated to withstand shear in service, is highly valuable because it maintains a high level of protection and performance and prolongs the life of the equipment.

Lubricants in commercial use today are prepared from a variety of natural and synthetic base stocks admixed with various additive packages and solvents depending upon their intended application. The base stocks typically include mineral polyalphaolefins (PAO), gas-to-liquid base oils (GTL), Fischer-Tropsch (F-T) oils, silicone oils, phosphate esters, diesters, polyol esters, alkylated aromatics and the like.

Viscosity index improvers are known to be added to lubricating oil compositions to improve the viscosity index of the lubricant. Typical viscosity index improvers include polymers of methacrylates, acrylates, olefins (such as copolymers of alpha-olefins and maleic anhydride and esterified derivatives thereof), or maleic anhydride-styrene copolymers, and esterified derivatives thereof. The viscosity index improvers tend to incorporate ester functional groups in pendant/grafted/branched groups. The ester functional groups may be derived from linear alkyl alcohols with 1 to 40 carbon atoms. Recent attempts have been made to produce viscosity index improvers from copolymers of alpha-olefins. However, such viscosity index improvers often have poor shear stability, too high a viscosity at low temperature, poor fuel economy, and poor non-dispersant cleanliness.

Lubricants capable of performing at lower viscosity (in, for instance, driveline devices) typically provide increased fuel economy (thus improving corporate average fuel efficiency (CAFE), NEDC (European Driving Cycle), or FTP-75 (Federal Test Procedure), or Japanese test cycle (JC-08)). Conversely, higher viscosity fluids contribute to elevated gear and transmission operating temperatures, which are believed to reduce fuel economy and diminish durability.

Driveline power transmitting devices such as gears or transmissions, especially axle fluids and manual transmission fluids (MTFs), present highly challenging technological problems and solutions for satisfying the multiple and often conflicting lubricating requirements, while at the same time providing at least one of wear performance, durability and fuel economy. One of the important parameters influencing performance is lubricant viscosity. Lubricants capable of performing at lower viscosity typically provide increased fuel economy (thus improving CAFE efficiency). Conversely, lower viscosity fluids also contribute to elevated gear and transmission operating temperatures, which are believed to reduce fuel economy. Additionally, increasing lubricant viscosity is believed to provide better wear protection and durability to gears and transmissions.

Consequently, it would be desirable to provide a correctly balanced lubricant composition to meet the needs of mechanical devices such as gears and transmissions, especially axle fluids and MTFs. The discovery of new was to control or adjust frictional properties of a tube formulation would be very beneficial.

The present disclosure provides solutions and advantages, which shall become apparent as described below.

SUMMARY

This disclosure relates in part to gear lubricant compositions containing a Group V co-base stock, in particular, an alkylated aromatic such as an alkylated naphthalene, that provide improved shear stability as measured by the KRL 20 hour Tapered Roller Bearing Test (CEC L-45-A-99).

This disclosure relates in part to a lubricating composition having a kinematic viscosity (Kv₁₀₀) from 5 to 32.5 cSt at 100° C., preferably from 6 to 20 cSt at 100° C., and more preferably from 8 to 13 cSt at 100° C., and a viscosity index (VI) from 140 to 200. The lubricating composition comprises: a bi-modal blend lubricating oil comprising from 20 to 99 weight percent, based on the total weight of the bi-modal blend lubricating oil, of a low viscosity basestock having a Kv₁₀₀ from 2 to 8 cSt at 100° C., and from 1 to 20 weight percent, based on the total weight of the bi-modal blend lubricating oil, of a high viscosity basestock having a Kv₁₀₀ from 40 to 600 cSt at 100° C.; a viscosity modifier comprising a copolymer having units derived from monomers of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol; and an alkylated aromatic co-base stock in an amount form 1 to 12 weight percent, based on the total weight of the lubricating composition, and having a Kv₁₀₀ from 3 to 15 cSt at 100° C., preferably 3 to 6 cSt at 100° C. Shear stability (as determined by CEC L-45-A-99) is improved in a driveline device lubricated with the lubricating composition as compared to shear stability achieved using a lubricating composition containing no co-base stock or a co-base stock other than the alkylated aromatic co-base stock.

This disclosure also relates in part to a process for producing the above lubricating composition. The process comprises: providing a bi-modal blend lubricating oil comprising from 20 to 99 weight percent of a low viscosity basestock having a Kv₁₀₀ from 2 to 8 cSt at 100° C., and from 1 to 20 weight percent of a high viscosity basestock having a Kv₁₀₀ from 40 to 600 cSt at 100° C.; providing a viscosity modifier comprising a copolymer having units derived from monomers of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol; providing an alkylated aromatic co-base stock in an amount form 1 to 12 weight percent and having a Kv₁₀₀ from 3 to 15 cSt at 100° C., preferably 3 to 6 cSt at 100° C.; and blending the bi-modal blend lubricating oil, viscosity modifier and alkylated aromatic co-base stock in amounts sufficient to produce the lubricating composition.

This disclosure further relates in part to a lubricant comprising the above lubricating composition, e.g., gear fluids, axle fluids and manual transmission fluids (MTFs).

This disclosure yet further relates in part to a method of lubricating a mechanical device comprising supplying to the device the above lubricating composition. The mechanical device comprises a driveline device, e.g., gears or transmissions.

This disclosure further relates in part to a method for improving fuel efficiency, while maintaining or improving shear stability in a driveline device, e.g., gears or transmissions, lubricated with a lubricating composition, by using the above lubricating composition.

In driveline devices such as axles, higher viscosity fluids can result in lower fuel efficiency due to churning losses. The internal friction of the fluid measured by its traction properties provide an indicator of its efficiency benefits in high pressure contact areas within axles. The method of blending of this disclosure delivers lower traction and lower viscosity fluids.

It has been surprisingly found that the lubricating compositions of this disclosure exhibit improved shear stability (as determined by CEC L-45-A-99) in a driveline device lubricated with said lubricating composition as compared to shear stability achieved with a lubricating composition containing no co-base stock or less than 4% co-base stock or a co-base stock other than the alkylated aromatic co-base stock. Unexpected improvements in viscosity loss can be achieved with lubricating compositions of this disclosure containing greater than 4 weight percent alkylated naphthalene, preferably 6 weight percent or 8 weight percent alkylated naphthalene, or greater, up to 12 weight percent.

Further objects, features and advantages of the present disclosure will be understood by reference to the following drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 graphically depicts KRL 20 hour shear test (as determined by CEC L-45-A-99) results for lubricating compositions in Example 1.

FIG. 2 shows ingredients for control gear oil formulations in Example 1 with varying amounts of alkylated naphthalene and KRL 20 hour shear test (as determined by CEC L-45-A-99) results.

FIG. 3 shows ingredients for control gear oil formulations in Example 1 with varying amounts of alkylated naphthalene and KRL, 20 hour shear test (as determined by CEC L-45-A-99) results.

DETAILED DESCRIPTION

All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

For purposes of this disclosure and the claims thereto, a polymer is referred to as comprising homopolymers and copolymers, where copolymers include any polymer having two or more chemically distinct monomers.

For the purposes of this disclosure and the claims thereto the term “polyalphaolefin,” “polyalphaolefin,” or “PAO” includes homopolymers and copolymers of C₃ or greater alphaolefin monomers.

The lubricating compositions of this disclosure exhibit improved shear stability in a driveline device lubricated with the lubricating composition as compared to shear stability achieved with a lubricating composition containing no co-base stock or a co-base stock other than the alkylated aromatic co-base stock.

The lubricating compositions of this disclosure are also capable of providing at least one of improved wear control, load carrying capacity, traction reduction, oxidative stability, reduced mechanical device operating temperatures, increased mechanical device durability, improved shear stability index, improved viscosity index, improved low temperature viscometrics and improved high temperature viscometrics.

In an embodiment, this disclosure relates to a combination of a bi-modal blend lubricating oil, an ester-containing viscosity modifier and an alkylated aromatic co-base stock that enables improvement in shear stability. Current commercial axle fluids are blended with low viscosity synthetic base stocks (such as <10 cSt PAO) in combination with conventional viscosity modifiers. In axles, higher viscosity fluids can result in lower fuel efficiency due to churning losses. The internal friction of the fluid measured by its traction properties provides an indicator of its efficiency benefits in high pressure contact areas within axles. The method of blending a bi-modal blend lubricating oil, an ester-containing viscosity modifier and an alkylated aromatic co-base stock in accordance with this disclosure provides lower traction and lower viscosity fluids.

This disclosure relates to lubricating driveline devices, e.g., gears and transmissions, using the lubricating oils to improve fuel efficiency without sacrificing driveline device durability.

Lubricating Oil Base Stocks

A wide range of lubricating oils is known in the art. Lubricating oils that are useful in the present disclosure are both natural oils and synthetic oils. Natural and synthetic oils (or mixtures thereof) can be used unrefined, refined, or rerefined (the latter is also known as reclaimed or reprocessed oil). Unrefined oils are those obtained directly from a natural or synthetic source and used without added purification. These include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from an esterification process. Refined oils are similar to the oils discussed for unrefined oils except refined oils are subjected to one or more purification steps to improve the at least one lubricating oil property. One skilled in the art is familiar with many purification processes. These processes include solvent extraction, secondary distillation, acid extraction, base extraction, filtration, and percolation. Rerefined oils are obtained by processes analogous to refined oils but using an oil that has been previously used as a feed stock.

Groups I, II, III, IV, V and VI are broad categories of base oil stocks developed and defined by the American Petroleum Institute (API Publication 1509; www.API.org) to create guidelines for lubricant base oils. Group I base stocks generally have a viscosity index of between 80 to 120 and contain greater than 0.03% sulfur and less than 90% saturates. Group II base stocks generally have a viscosity index of between 80 to 120, and contain less than or equal to 0.03% sulfur and greater than or equal to 90% saturates. Group III stock generally has a viscosity index greater than 120 and contains less than or equal to 0.03% sulfur and greater than 90% saturates. Group IV includes polyalphaolefins (PAO). Group V base stocks include base stocks not included in Groups I-IV. The table below summarizes properties of each of these six groups.

Group VI are polyinternal olefins (“PIO”). Polyinternal olefins are long-chain hydrocarbons, typically a linear backbone with some branching randomly attached; they are obtained by oligomerization of internal n-olefins. The catalyst is usually a BF3 complex with a proton source that leads to a cationic polymerization, or promoted BF3 or AlCl3 catalyst system. The process to produce polyinternal olefins (PIO) consists of four steps: reaction, neutralization/washing, hydrogenation and distillation. These steps are somewhat similar to PAO process. PIO are typically available in low viscosity grades, 4 cSt, 6 cSt and 8 cSt. If necessary, low viscosity, 1.5 to 3.9 cSt can also be made conveniently by the BF3 process or other cationic processes. Typically, the n-olefins used as starting material are n-C₁₂-C₁₈ internal olefins, more preferably, n-C₁₄-C₁₆ olefins are used. PIO can be made with VI and pour points very similar to PAO, only slightly inferior. They can be used in engine and industrial lubricant formulations. For more detailed discussion, see Chapter 2, Polyinternalolefins in the book, “Synthetics, Mineral Oils, and Bio-Based Lubricants—Chemistry and Technology” Edited by Leslie R. Rudnick, p. 37-46, published by CRC Press, Taylor & Francis Group, 2006; or “Polyinternal Olefins” by Corsico, G.; Mattel, L.; Roselli, A.; Gommellini, Carlo. EURON, Milan, Italy. Chemical Industries (Dekker) (1999), 77 (Synthetic Lubricants and High-Performance Functional Fluids, (2nd Edition)), 53-62. Publisher: Marcel Dekker, Inc. PIO was classified by itself as Group VI fluid in API base stock classification.

Base Stock Properties Saturates Sulfur Viscosity Index Group I <90 and/or >0.03% and ≧80 and <120 Group II ≧90 and ≦0.03% and ≧80 and <120 Group III ≧90 and ≦0.03% and ≧120 Group IV Includes polyalphaolefins (PAO) Group V All other base oil stocks not included in Group VI Groups I, II, III or IV Polyinternal olefins (PIO)

Natural oils include animal oils, vegetable oils (castor oil and lard oil, for example), and mineral oils. Animal and vegetable oils possessing favorable thermal oxidative stability can be used. Of the natural oils, mineral oils are preferred. Mineral oils vary widely as to their crude source, for example, as to whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful in the present disclosure. Natural oils vary also as to the method used for their production and purification, for example, their distillation range and whether they are straight run or cracked, hydrorefined, or solvent extracted.

Group II and/or Group III hydroprocessed or hydrocracked base stocks, as well as synthetic oils such as polyalphaolefins, alkyl aromatics and synthetic esters, i.e., Group IV and Group V oils are also well known base stock oils.

Synthetic oils include hydrocarbon oil such as polymerized and interpolymerized olefins (polybutylenes, polypropylenes, propylene isobutylene copolymers, ethylene-olefin copolymers, and ethylene-alphaolefin copolymers, for example). Polyalphaolefin (PAO) oil base stocks, the Group IV API base stocks, are a commonly used synthetic hydrocarbon oil. By way of example, PAOs derived from C₈, C₁₀, C₁₂, C₁₄ olefins or mixtures thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064; and 4,827,073, which are incorporated herein by reference in their entirety. Group IV oils, that is, the PAO base stocks have viscosity indices preferably greater than 130, more preferably greater than 135, still more preferably greater than 140.

Esters in a minor amount may be useful in the lubricating oils of this disclosure. Additive solvency and seal compatibility characteristics may be secured by the use of esters such as the esters of dibasic acids with monoalkanols and the polyol esters of monocarboxylic acids. Esters of the former type include, for example, the esters of dicarboxylic acids such as phthalic acid, succinic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc., with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types of esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

Particularly useful synthetic esters are those which are Obtained by reacting one or more polyhydric alcohols, preferably the hindered polyols such as the neopentyl polyols; e.g., neopentyl glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane, pentaerythritol and dipentaerythritol with alkanoic acids containing at least 4 carbon atoms, preferably C₅ to C₃₀ acids such as saturated straight chain fatty acids including caprylic acid, capric acids, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, and behenic acid, or the corresponding branched chain fatty acids or unsaturated fatty acids such as oleic acid, or mixtures of any of these materials.

Esters should be used in a amount such that the improved wear and corrosion resistance provided by the lubricating oils of this disclosure are not adversely affected. The esters preferably have a D5293 viscosity of less than 10,000 cP at −35° C.

Non-conventional or unconventional base stocks and/or base oils include one or a mixture of base stock(s) and/or base oil(s) derived from: (1) one or more Gas-to-Liquids (GTL) materials, as well as (2) hydrodewaxed, or hydroisomerized/cat (and/or solvent) dewaxed base stock(s) and/or base oils derived from synthetic wax, natural wax or waxy feeds, mineral and/or non-mineral oil waxy feed stocks such as gas oils, slack waxes (derived from the solvent dewaxing of natural oils, mineral oils or synthetic oils; e.g., Fischer-Tropsch feed stocks), natural waxes, and waxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal crackates, foots oil or other mineral, mineral oil, or even non-petroleum oil derived waxy materials such as waxy materials recovered from coal liquefaction or shale oil, linear or branched hydrocarbyl compounds with carbon number of 20 or greater, preferably 30 or greater and mixtures of such base stocks and/or base oils.

GTL materials are materials that are derived via one or more synthesis, combination, transformation, rearrangement, and/or degradation/deconstructive processes from gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks such as hydrogen, carbon dioxide, carbon monoxide, water, methane, ethane, ethylene, acetylene, propane, propylene, propyne, butane, butylenes, and butynes. GTL base stocks and/or base oils are GTL materials of lubricating viscosity that are generally derived from hydrocarbons; for example, waxy synthesized hydrocarbons, that are themselves derived from simpler gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks. GTL base stock(s) and/or base oil(s) include oils boiling in the lube oil boiling range (1) separated/fractionated from synthesized GTL materials such as, for example, by distillation and subsequently subjected to a final wax processing step which involves either or both of a catalytic dewaxing process, or a solvent dewaxing process, to produce lube oils of reduced/low pour point; (2) synthesized wax isomerates, comprising, for example, hydrodewaxed or hydroisomerized cat and/or solvent dewaxed synthesized wax or waxy hydrocarbons; (3) hydrodewaxed or hydroisomerized cat and/or solvent dewaxed Fischer-Tropsch (F-T) material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possible analogous oxygenates); preferably hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxing dewaxed waxy hydrocarbons, or hydrodewaxed or hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T waxes, or mixtures thereof.

GTL base stock(s) and/or base oil(s) derived from GTL materials, especially, hydrodewaxed or hydroisomerized/followed by cat and/or solvent dewaxed wax or waxy feed, preferably F-T material derived base stock(s) and/or base oil(s), are characterized typically as having kinematic viscosities at 100° C. of from 2 mm²/s to 50 mm²/s (ASTM D445) They are further characterized typically as having pour points of −5° C. to −40° C. or lower (ASTM D97). They are also characterized typically as having viscosity indices of 80 to 140 or greater (ASTM D2270).

In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monoycloparaffins and multicycloparaffins in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than 10 ppm, and more typically less than 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, is essentially nil. In addition, the absence of phosphorous and aromatics make this materially especially suitable for the formulation of low SAP products.

The term GTL base stock and/or base oil and/or wax isomerate base stock and/or base oil is to be understood as embracing individual fractions of such materials of wide viscosity range as recovered in the production process, mixtures of two or more of such fractions, as well as mixtures of one or two or more low viscosity fractions with one, two or more higher viscosity fractions to produce a blend wherein the blend exhibits a target kinematic viscosity.

The GTL material, from which the GTL base stock(s) and/or base oil(s) is/are derived is preferably an F-T material (i.e., hydrocarbons, waxy hydrocarbons, wax).

Base oils for use in the formulated lubricating oils useful in the present disclosure are any of the variety of oils corresponding to API Group I, Group II, Group III, Group IV, Group V and Group VI oils and mixtures thereof, preferably API Group II, Group iii, Group IV, Group V and Group VI oils and mixtures thereof, more preferably the Group m to Group VI base oils due to their exceptional volatility, stability, viscometric and cleanliness features. Minor quantities of Group I stock, such as the amount used to dilute additives for blending into formulated lube oil products, can be tolerated but should be kept to a minimum, i.e. amounts only associated with their use as diluent/carrier oil for additives used on an “as-received” basis. Even in regard to the Group II stocks, it is preferred that the Group II stock be in the higher quality range associated with that stock, i.e. a Group II stock having a viscosity index in the range 100<VI<120.

In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monocycloparaffins and multicycloparaffins in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) and hydrodewaxed, or hydroisomerized/cat (and/or solvent) dewaxed base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than 10 ppm, and more typically less than 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, is essentially nil. In addition, the absence of phosphorous and aromatics make this material especially suitable for the formulation of low sulfur, sulfated ash, and phosphorus (low SAP) products.

Polyalphaolefins (PAOs) are preferred lubricating oil basestocks of this disclosure. The PAOs can preferably comprise one or more C₈ to C₁₄, preferably C₈ to C₁₂ monomers. The PAOs have a viscosity (Kv₁₀₀) from 5 to 32.5 cSt at 100° C., preferably 6 to 15 cSt at 100° C., and more preferably from 8 to 13 cSt, and a viscosity index (VI) from 140 to 200.

With reference to the bi-modal blend lubricating oils of this disclosure, the high viscosity base stock can range from 40 to 600 cSt at 100° C., and the low viscosity base stock can range from 2 to 8 cSt at 100° C. Concentration ratios of high viscosity base stock to low viscosity base stock can range from 25:1 to 1:25. As used herein, viscosity (Kv₁₀₀) is determined by ASTM D 445-01, and viscosity index (VI) is determined by ASTM D 2270-93 (1998).

The PAOs useful in this disclosure can have a pour point (PP) less than −25° C.; a molecular weight distribution (Mw/Mn) less than 2.0; and a glass transition temperature T_(g) less than −60° C.

In another embodiment according to the present disclosure, any PAO described herein may have a kinematic viscosity (Kv) at 100° C. in any of the following ranges: from 65 to 1,000 cSt, from 100 to 950 cSt, from 250 cSt to 900 cSt, from 400 cSt to 800 cSt, wherein all values are measured by ASTM D445-01.

The low viscosity PAOs useful in this disclosure have a high viscosity index and a Kv₁₀₀ of 5 cSt or more, alternatively 6 cSt or more, alternatively 8 cSt or more, up to 20 cSt, with a VI of 110 or more, alternatively 115 or more, alternatively 120 or more. The high viscosity PAOs useful in this disclosure have a high viscosity index and a Kv₁₀₀ of 35 cSt or more, alternatively 40 cSt or more, alternatively 150 cSt or more, up to 600 cSt, with a VI of 140 or more, alternatively 180 or more, alternatively 200 or more. Usually base stock VI is a function of fluid viscosity. Usually, the higher the VI, the better it is for lube application. Base stock VI also depends on feed composition. Fluids made from single 1-octene, 1-nonene, 1-decene, or 1-dodecene have excellent VI and good low pour point. Fluids made from two or more olefins selected from C₈ to C₁₂ alphaolefins generally have excellent high VI and superior low pour points if the average carbon chain length of feed LAOs is kept within 8 to 12 carbons. A relatively much lower average chain length in the feed (much below 6 carbons) of the mixed LAO can result in lower VI. Too high of a average chain length in the feed (much above 12 carbons) of the mixed LAO would result in very high pour point, around room temperature.

In another embodiment according to the present disclosure, any polyalphaolefin described herein has a viscosity index (VI) of 110 or more, or 120 or more, or 130 or more; alternatively, from 110 to 140, alternatively from 140 to 180, alternatively from 180 to 200, or greater. Viscosity index is determined according to ASTM Method D2270-93 [1998].

The viscosity-temperature relationship of lubricating oil is one of the critical criteria which must be considered when selecting a lubricant for a particular application. Viscosity Index (VI) is an empirical, unitless number which indicates the rate of change in the viscosity of an oil within a given temperature range and is related to kinematic viscosities measured at 40° C. and 100° C. (typically using ASTM Method D 445). Fluids exhibiting a relatively large change in viscosity with temperature are said to have a low viscosity index. The low VI oil, for example, will thin out at elevated temperatures faster than the high VI oil. Usually, the high VI oil is more desirable because it has higher viscosity at higher temperature, which translates into better or thicker lubrication film and better protection of the contacting machine elements. As the oil operating temperature decreases, the viscosity of the high VI oil will not increase as much as the viscosity of low VI oil. This is advantageous because the excessive high viscosity of the low VI oil will decrease the efficiency of the operating machine. Thus high VI oil has performance advantages in both high and low temperature operation.

The PAOs useful in this disclosure have low pour points (PP) less than −25° C., preferably less than −30° C., and more preferably less than −35° C. As used herein, pour point is determined by ASTM D97.

In an embodiment of this disclosure, any PAO described herein may have a pour point of less than −25° C. (as measured by ASTM D97), preferably less than −35° C., preferably less than −45° C., preferably less than −55° C., preferably less than −65° C., and preferably between −25° C. and −75° C.

The PAOs useful in this disclosure have a narrow molecular weight distribution (Mw/Mn) less than 2.0, preferably less than 1.95, and more preferably less than 1.9 as synthesized, and even more preferably 1% as synthesized, As used herein, molecular weight distribution (Mw/Mn) is determined by GPC using a column for medium to low molecular weight polymers, tetrahydrofuran as solvent and polystyrene as calibration standard.

The PAOs useful in this disclosure have a Mw of 100,000 g/mol or less, or between 2000 and 80,000 g/mol, or between 2500 and 60,000 g/mol, or between 2800 and 50,000 g/mol, or between 3360 and 40,000 g/mol. Preferred Mw's include those from 840 to 55,100 g/mol, or from 900 to 45,000 g/mol, or 1000 to 40,000 g/mol, or 2,000 to 37,500 g/mol. Alternatively preferred Mw's include 2240 to 67900 g/mol and 2240 to 37200 g/mol. The bi-modal blend lubricating oils of this disclosure can comprise combinations of these PAOs.

The PAOs useful in this disclosure preferably have an Mn of 50,000 g/mol or less, or 40,000 g/mol or less, or between 2000 and 40,000 g/mol, or between 2500 and 30,000 g/mol, preferably between 5000 and 20,000 g/mol. Preferred Mn ranges include those from 2800 to 10,000 g/mol or from 2800 to 8,000 g/mol. Alternatively preferred Mn ranges are from 2000 to 20,900 g/mol, or 2800 to 20,000 g/mol, or 2000 to 17000 g/mol, or 2000 to 12000 g/mol, or 2800 to 29000 g/mol, or 2800 to 17000 g/mol, or 2000 to 5000 g/mol.

The Mw and Mn are measured by GPC using a column for medium to low molecular weight polymers, tetrahydrofuran as solvent and polystyrene as calibration standard, correlated with the fluid viscosity according to a power equation.

In another embodiment, the PAOs described herein have a narrow molecular weight distribution of greater than, or equal to, 1 and less than 2, alternatively less than 1.95, alternatively less than 1.90, alternatively less than 1.85. The Mn and Mw are measured by gel permeation chromatography (GPC) using a column for medium to low molecular weight polymers, tetrahydrofuran as solvent and narrow molecular weight distribution polystyrene as calibration standard, correlated with the fluid viscosity according to a power equation. The MWD of PAO is a function of fluid viscosity. Alternatively any of the polyalphaolefins described herein preferably have an Mw/Mn of between 1 and 2.0, alternatively between 1 and 1.95, depending on fluid viscosity.

The PAOs useful in this disclosure have low glass transition temperature T_(g) less than −60° C., preferably less than −70° C., and more preferably less than −80° C. The bi-modal blend lubricating oils of this disclosure can comprise combinations of these PAOs. As used herein, glass transition temperature T_(g) is determined by differential scanning calorimetry (DSC). The polyolefin products produced in accordance with the process of this disclosure have no crystallization peak as measured by differential scanning calorimetry and high thermal stability.

The PAOs useful in this disclosure can comprise a single alphaolefin monomer type, or may comprise two or more different alphaolefin monomers. In one embodiment, this disclosure relates to PAOs comprising a molar amount of C₈ to C₁₂ alphaolefin monomers selected from the group consisting of 55 mol % or more, 60 mol % or more, 65 mol % or more, 70 mol % or more, 75 mol % or more, 80 mol % or more, 85 mol % or more, 90 mol % or more, 95 mol % or more, 100 mol %, all based on the total moles of monomers present in the polyalphaolefin, as measured by ¹³C NMR. When two or more alphaolefin monomers are present, it is sometimes desirable to add propylene, or butene (typically 1-butene) olefins into the feed. Use of these smaller olefins in the feed offers the advantage of lower feed cost and/or more abundant feed source. When adding C₃ or 1-C₄ olefins as one of the feed components, it is important to maintain the total average carbon chain length of the feed LAO (linear alphaolefin) between 8 to 12 carbons.

In one or more embodiments, the PAOs comprise polymers of one or more alphaolefins (also known as 1-olefins) with carbon numbers of C₈ to C₁₂. Preferably, at least one of the alphaolefins is a linear alphaolefin (LAO); more preferably, all the alphaolefins are LAOS. Suitable LAOs include 1-octene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene, and blends thereof.

In one or more embodiments, the PAO comprises polymers of two or more C₈ to C₁₂ LAOs to make ‘copolymer’ or ‘terpolymer’ or higher-order copolymer combinations. Other embodiments involve polymerization of a mixture of LAOs selected from C₈ to C₁₂ LAOs with even carbon numbers, preferably a mixture of two or three LAOs selected from 1-octene, 1-decease, and 1-dodecene.

In one or more embodiments, the PAO comprises polymers of a single alphaolefin species having a total carbon count of 8 to 12. In other embodiments, the PAO comprises polymers of mixed (i.e., two or more) alphaolefin species, wherein each alphaolefin species has a carbon number of 8 to 12. In other embodiments, the PAO comprises polymers of mixed alphaolefin species wherein the molar-average carbon number (“C_(LAO)”) is 8 to 12 or 9 to 11.

In another embodiment according to the present disclosure, any PAO described herein may have a density of 0.75 to 0.96 g/cm³, preferably 0.80 to 0.94 g/cm³, alternatively from 0.76 to 0.855 g/cm³.

The high viscosity PAOs useful in this disclosure are desirable for use as lubricating oil base stocks and also blend stocks with API Groups I to V or gas-to-liquid (GTL) derived lube base stocks for use in industrial and automotive engine or gear oil, especially certain high Kv₁₀₀ grades of 40 to 600 cSt which are especially desirable for use as lubricating oil base stocks or blend stocks with Groups I to V or GTL-derived lube base stocks for use in industrial and automotive engine or gear oil formulations. The bi-modal blend lubricating oils of this disclosure can comprise combinations of these PAOs, Groups I to V, and GTL-derived lube base stocks.

These higher viscosity PAOs can be used as lubricating oil base stocks and also superior blend stocks. They can be blend stocks with any of the API Group I to V and GTL fluids to give the optimum viscometrics, solvency, high and low temperature lubricity, etc. The PAOs can be further blended with proper additives, including antioxidants, antiwear additives, friction modifiers, dispersants, detergents, corrosion inhibitors, defoamants, extreme pressure additives, seal swell additives, and optionally viscosity modifiers, etc. Description of typical additives can be found in the book “Lubricant Additives: Chemistry and Applications,” L. R. Rudnick, ed. Marcel Dekker Inc., New York, 2001.

The PAOs can be produced by conventional methods known in the art.

The basestock component of the present lubricating oils will typically be from 80 to 99 weight percent of the total composition (all proportions and percentages set out in this specification are by weight unless the contrary is stated) and more usually in the range of 90 to 99 weight percent.

Viscosity Modifiers

The viscosity modifiers useful in the lubricating compositions of the disclosure include substantially linear polymers with a weight average molecular weight of 45,000 or less, or 35,000 or less, or 25,000 or less, or 8000 to 25,000, or 12,000 to 20,000.

The substantially linear polymers may be copolymers comprising units derived from monomers (1) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol. In one embodiment, the substantially linear polymer may be a copolymer comprising units derived from monomers (i) one or more alpha olefins and (ii) one or more alkyl (meth)acrylate esters. The ethylenically unsaturated carboxylic acid may be esterified with alcohol before or after polymerization with the α-olefin. In one embodiment the ethylenically unsaturated carboxylic acid may be esterified with alcohol before polymerization with the α-olefin. In one embodiment the ethylenically unsaturated carboxylic acid may be esterified with alcohol after polymerization with the α-olefin.

A commercially available copolymer prepared by esterification before polymerization is available from Akzo Nobel sold under the tradename Ketjenlube®3700. The alcohol may have 1 to 40, or 1 to 30, or 4 to 20, or 6 to 16 carbon atoms. Examples of a suitable alcohol include 2-ethylhexanol, 2-butyloctanol, 2-hexyldecanol, 2-octyldodecanol, 2-decyltetradecanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, eicosanol, or mixtures thereof. A copolymer of this type is described in more detail in U.S. Pat. Nos. 4,526,950, 6,419,714, 6,573,224, or 6,174,843.

The ethylenically unsaturated carboxylic acid may be esterified with alcohol after polymerization with the α-olefin. A copolymer of this type may be a substantially linear polymer that may in one embodiment be (a) a copolymer comprising units derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer typically has a reduced specific viscosity of up to 0.2, (b) a poly(meth)acrylate, or mixtures thereof.

The substantially linear polymer may be present in the lubricating compositions described herein at 0.1 wt % to 50 wt %, or 2 wt % to 40 wt %, or 5 wt % to 30 wt %, or 8 wt % to 20 wt % of the lubricating composition. In certain embodiments the lubricating composition contains 65 to 99 wt % of synthetic base stock and 1 to 35 wt % of substantially linear polymer. In other embodiments, the lubricating composition contains 75 to 98 wt % of synthetic base stock and 2 to 25 wt % of substantially linear polymer.

In one embodiment, the substantially linear polymer may be a copolymer comprising units derived from monomers (i) one or more alpha olefins and (ii) one or more alkyl (meth)acrylate esters. In another embodiment the substantially linear polymer includes a mixtures of (a) a copolymer comprising units derived from monomers of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol, and (b) a poly(meth)acrylate.

The poly(meth)acrylate (typically a polymethacrylate) can have units derived from a mixture of alkyl (meth)acrylate ester monomers containing (a) 8 to 24, or 12 to 18, or to 15 carbon atoms in the alcohol-derived portion of the ester group and (b) 6 to 11, or 8 to 11, or 8 carbon atoms in the alcohol-derived portion of the ester group, and which have 2-(C₁₋₄ alkyl)-substituents, and optionally, at least one monomer selected from the group consisting of (meth)acrylic acid esters containing 1 to 7 carbon atoms in the alcohol-derived portion of the ester group and which are different from (meth)acrylic acid esters (a) and (b), vinyl aromatic compounds (or vinyl aromatic monomers); and nitrogen-containing vinyl monomers; provided that no more than 60% by weight, or no more than 50% by weight, or no more than 35% by weight of the esters contain not more than 10 carbon atoms in the alcohol-derived portion of the ester group. The linear polymer of this type is described in more detail in U.S. Pat. No. 6,124,249 or EP 0 937 769 A1. The “alcohol-derived portion” refers to the “—OR” portion of an ester, when written as R′C(=0)—OR, whether or not it is actually prepared by reaction with an alcohol. Optionally, the linear polymer may further contain a third monomer. The third monomer may be styrene, or mixtures thereof. The third monomer may be present in an amount 0% to 25% of the polymer composition, or from 1% to 15% of the composition, 2% to 10% of the composition, or even from 1% to 3% of the composition.

Typically, the mole ratio of esters (a) to esters (b) in the copolymer ranges from 95:5 to 35:65, or 90:10 to 60:40, or 80:20 to 50:50.

The esters are usually aliphatic esters, typically alkyl esters. In one embodiment the ester of (a) may be a C₁₂₋₁₅ alkyl methacrylate and the ester of (b) may be 2-ethylhexyl methacrylate.

In one embodiment, the ester groups in ester (a) contain branched alkyl groups. The ester groups may contain 2 to 65%, or 5 to 60% or greater of the ester groups having branched alkyl groups.

The C₁₋₄ alkyl substituents may be methyl, ethyl, and any isomers of propyl and butyl.

The weight average molecular weight of the poly(meth)acrylate may be 45,000 or less, or 35,000 or less, or 25,000 or less, or 8000 to 25,000, or 12,000 to 20,000.

In one embodiment the substantially linear polymer includes a copolymer comprising units derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer typically has a reduced specific viscosity of up to 0.2, or up to 0.15, or up to 0.10, or up to 0.08. In one embodiment the reduced specific viscosity may be up to 0.08 (or 0.02 to 0.08 (or 0.02 to 0.07, 0.03 to 0.07 or 0.04 to 0.06).

A measurement correlating with molecular weight of the copolymer (or interpolymer such as an alternating copolymer) may be expressed in terms of the “reduced specific viscosity” of the copolymer which is a recognized means of expressing the molecular size of a polymeric substance. As used herein, the reduced specific viscosity (abbreviated as RSV) is the value typically obtained in accordance with the formula RSV=(Relative Viscosity−1)/Concentration, wherein the relative viscosity is determined by measuring, by means of a dilution viscometer, the viscosity of a solution of 1.6 g of the polymer in 100 cm³ of acetone and the viscosity of acetone at 30° C. For purpose of computation by the above formula, the concentration is adjusted to 1.6 g of the copolymer per 100 cm³ of acetone. A more detailed discussion of the reduced specific viscosity, also known as the specific viscosity, as well as its relationship to the average molecular weight of a copolymer, appears in Paul. J. Flory, Principles of Polymer Chemistry, (1953 Edition) pages 308 et seq.

In one embodiment the copolymer may be derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof,

wherein 0.1 to 99.89 percent of the carboxylic acid units are esterified with a primary alcohol branched at the β- or higher position,

wherein 0.1 to 99.89 percent of the carboxylic acid units are esterified with a linear alcohol or an alpha-branched alcohol (e.g., a secondary alcohol),

wherein 0.01 to 10% of the carboxylic acid units has at least one of an amino-, amido- and/or imido-group, and

wherein the copolymer has a reduced specific viscosity (prior to esterification) of up to 0.08.

In one embodiment the copolymer may be derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof,

wherein 0.1 to 99.89 percent of the carboxylic acid units are esterified with a primary alcohol branched at the [beta]- or higher position,

wherein 0.1 to 99.9 percent of the carboxylic acid units are esterified with a linear alcohol or an alpha-branched alcohol,

wherein 0 to 10% of the carboxylic acid units has at least one of an amino-, amido- and/or imido-group, and

wherein the copolymer has a reduced specific viscosity of up to 0.08.

A linear alcohol may include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, or mixtures thereof. In one embodiment the linear alcohol contains 6 to 30, or 8 to 20, or 8 to 15 carbon atoms (typically 8 to 15 carbon atoms).

The linear alcohol may include commercially available materials such as Oxo Alcohol® 7911, Oxo Alcohol® 7900 and Oxo Alcohol® 1 100 of Monsanto; Alphanol® 79 of ICI; Nafol® 1620, Alfol® 610 and Alfol® 810 of Condea (now Sasol); Epal® 610 and Epal® 810 of Ethyl Corporation (now Afton); Linevol® 79, Linevol® 91 1 and Dobanol® 25 L of Shell AG; Lial® 125 of Condea Augusta, Milan; Dehydad® and Lorol® of Henkel KGaA (now Cognis) as well as Linopol® 7-1 1 and Acropol® 91 of Ugine Kuhlmann.

In one embodiment the copolymer may be derived from monomers of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof,

wherein 5 to 15 percent of the carboxylic acid units are esterified with a primary alcohol branched at the β- or higher position,

wherein 0.1 to 95 percent of the carboxylic acid units are esterified with a linear alcohol or an alpha-branched alcohol,

wherein 0 to less than 2% of the carboxylic acid units has at east one of an amido- and/or imido-group, and

wherein the copolymer has a reduced specific viscosity of up to 0.08.

In one embodiment the copolymer comprises units derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position. In certain embodiments the copolymer may be represented by the formula below. Ester or other groups with the primary alcohol-derived moiety branched at the β- or higher position may be represented within the ( )_(w) shown in the formula:

wherein

Formula (I) may comprise a copolymer backbone (BB), and one or more pendant groups as shown, wherein BB may be derived from a copolymer of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof (typically fumaric acid, maleic anhydride, maleic acid, (meth)acrylic acid, itaconic anhydride or itaconic acid);

X may be a functional group which either (i) contains a carbon and at least one oxygen or nitrogen atom (such as an ester or amide, or imide linkage), or (ii) is an alkylene group with 1 to 5 carbon atoms (typically —CH2-), connecting the copolymer backbone and a branched hydrocarbyl group contained within ( )_(y), (typically X may be a functional group which either (i) contains a carbon and at least one oxygen or nitrogen atom);

w may be the number of pendant groups attached to the copolymer backbone, which may be in the range of 2 to 2000, or 2 to 500, or 5 to 250;

y may be 0, 1, 2 or 3, provided that in at least 1 mol % of the pendant groups, y is not zero; and with the proviso that when y is 0, X is bonded to a terminal group in a manner sufficient to satisfy the valence of X, wherein the terminal group is selected from hydrogen, alkyl, aryl, a metal (typically introduced during neutralization of ester reactions; suitable metals include calcium, magnesium, barium, zinc, sodium, potassium or lithium) or ammonium cation, and mixtures thereof;

p may be an integer in the range of 1 to 15 (or 1 to 8, or 1 to 4); and

R′ and R″ may independently be linear or branched hydrocarbyl groups, and the combined total number of carbon atoms present in R′ and R″ may be at least 12 (or at least 16, or at least 18 or at least 20).

In different embodiments the copolymer with pendant groups may contain 0.10% to 100%, or 0.5% to 20%, or 0.75% to 10%, branched hydrocarbyl groups represented by a group within ( )_(y) of the formula above, expressed as a percentage of the total number of pendant groups. The pendant groups of formula (1) may also be used to define the ester groups as defined above by the phrase “esterified with a primary alcohol branched at the β- or higher position”.

In different embodiments the functional groups defined by X on the formula above, may comprise at least one of —CO₂—, —C(O)N═ or —(CH2)_(v)-, wherein v is an integer in the range of 1 to 20, or 1 to 10, or 1 to 2.

In one embodiment X may be derived from an ethylenically unsaturated carboxylic acid or derivatives thereof. Examples of a suitable carboxylic acid or derivatives thereof typically include maleic anhydride, maleic acid, (meth)acrylic acid, itaconic anhydride or itaconic acid. In one embodiment the ethylenically unsaturated carboxylic acid or derivatives thereof may be at least one of maleic anhydride or maleic acid.

In one embodiment X is other than an alkylene group, connecting the copolymer backbone and the branched hydrocarbyl groups.

In different embodiments the pendant groups may be esterified, amidated or imidated functional groups.

In one embodiment the pendant groups may be derived from esterified and/or amidated functional groups.

In one embodiment the copolymer includes esterified pendant groups. The pendant groups may be derived from Guerbet alcohols. The Guerbet alcohols may contain 10 to 60, or 12 to 60, or 16 to 40 carbon atoms. In one embodiment the primary alcohol branched at the β- or higher position described herein may be a Guerbet alcohol. Methods to prepare Guerbet alcohols are disclosed in U.S. Pat. No. 4,767,815.

Examples of suitable groups for R′ and R″ on the formula defined above include the following:

1) alkyl groups containing C₁₅₋₁₆ polymethylene groups, such as 2-C₁₋₁₅ alkyl-hexadecyl groups 2-octylhexadecyl) and 2-alkyl-octadecyl groups (e.g., 2-ethyloctadecyl, 2-tetradecyl-octadecyl and 2-hexadecyloctadecyl);

2) alkyl groups containing C₁₃₋₁₄ polymethylene groups, such as 1-C₁₋₁₅ alkyl-tetradecyl groups (e.g., 2-hexyltetradecyl, 2-decyltetradecyl and 2-undecyltridecyl) and 2-C₁₋₁₅ alkyl-hexadecyl groups (e.g., 2-ethyl-hexadecyl and 2-dodecylhexadecyl);

3) alkyl groups containing C₁₀₋₁₂ polymethylene groups, such as 2-C₁₋₁₅ alkyl-dodecyl groups (e.g., 2-octyldodecyl) and 2-C₁₋₁₅ alkyl-dodecyl groups (2-hexyldodecyl and 2-octyldodecyl), 2-C₁₋₁₅ alkyl-tetradecyl groups (e.g., 2-hexyltetradecyl and 2-decyltetradecyl);

4) alkyl groups containing C₆₋₉ polymethylene groups, such as 2-C₁₋₁₅ alkyl-decyl groups (e.g., 2-octyldecyl) and 2,4-di-C₁₋₁₅ alkyl-decyl groups (e.g., 2-ethyl-4-butyl-decyl group);

5) alkyl groups containing C₁₋₅ polymethylene groups, such as 2-(3-methylhexyl)-7-methyl-decyl and 2-(1,4-dimethylbutyl-5,7,7-trimethyl-octyl groups; and 6) and mixtures of two or more branched alkyl groups, such as alkyl residues of oxoalcohols corresponding to propylene oligomers (from hexamer to undecamer), ethylene/propylene (molar ratio 16:1-1:11) oligomers, iso-butene oligomers (from pentamer to octamer), C₅₋₁₇ α-olefin oligomers (from dimer to hexamer).

The pendant groups may contain a total combined number of carbon atoms on R′ and R″ in the range of 12 to 60, or 14 to 50, or 16 to 40, or 18 to 40, or 20 to 36.

Each of R′ and R″ may individually contain 5 to 25, or 8 to 32 or 10 to 18 methylene carbon atoms. In one embodiment the number of carbon atoms on each R′ and R″ group may be 10 to 24.

Examples of suitable primary alcohol branched at the 3- or higher position include 2-ethylhexanol, 2-propyl heptanol, 2-butyloctanol, 2-hexyldecanol, 2-octyldodecanol, 2-decyltetradecanol, or mixtures thereof.

The ethylenically unsaturated carboxylic acid or derivatives thereof may be an acid or anhydride or derivatives thereof that may be wholly esterified, partially esterified or mixtures thereof. When partially esterified, other functional groups include acids, salts or mixtures thereof. Suitable salts include alkali metals, alkaline earth metals or mixtures thereof. The salts include lithium, sodium, potassium, magnesium, calcium or mixtures thereof. The unsaturated carboxylic acid or derivatives thereof includes acrylic acid, methyl acrylate, methacrylic acid, maleic acid or anhydride, fumaric acid, itaconic acid or anhydride or mixtures thereof, or substituted equivalents thereof.

Suitable examples of the ethylenically unsaturated carboxylic acid or derivatives thereof include itaconic anhydride, maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, dimethyl maleic anhydride or mixtures thereof.

In one embodiment the ethylenically unsaturated carboxylic acid or derivatives thereof includes maleic anhydride or derivatives thereof.

Examples of an alpha-olefin include 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-hepta-decene 1-octadecene, or mixtures thereof. An example of a useful alpha-olefin is 1-dodecene. The alpha-olefin may be a branched alpha-olefin, or mixtures thereof. If the a-olefin is branched, the number of carbon atoms of the α-olefin may range from 4 to 32, or 6 to 20, or 8 to 16.

In one embodiment the copolymer of the disclosure further includes a nitrogen containing group such as those disclosed above. The nitrogen containing group may be derived from a nitrogen containing compound capable of being incorporated during copolymerization. In one embodiment the copolymer of the disclosure further includes a nitrogen containing group that may be capable of reacting with the functionalized copolymer backbone, typically for capping the copolymer backbone. The capping may result in the copolymer having ester, amide, imide or amine groups. The nitrogen group is described in more detail in PCT Patent Application No. PCT/US09/052028.

In one embodiment the copolymer comprises units derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof may be further reacted with an amine to additionally provide oxidation control. Typically, the copolymer with oxidation control contains an incorporated residue of an amine-containing compound such as morpholines, pyrrolidinones, imidazolidinones, acetamides, β-alanine alkyl esters, or mixtures thereof. Examples of suitable nitrogen-containing compounds include 3-morpholin-4-yl-propylamine, 3-morpholin-4-yl-ethylamine, [beta]-alanine alkyl esters (typically alkyl esters have 1 to 30, or 6 to 20 carbon atoms), or mixtures thereof.

In one embodiment the compounds based on imidazolidinones, cyclic carbamates or pyrrolidinones may be derived from a compound of general structure:

wherein:

X=—OH or NH2;

Hy″ may be hydrogen, or a hydrocarbyl group (typically alkyl, or C₁₋₄, or C²⁻ alkyl); Hy may be a hydrocarbylene group (typically alkyl ene, or C₁₋₄, or C²⁻ alkylene); Q=>NH, >NR, >CH₂, >CHR, >CR₂, or —O— (typically >NH, or >NR) and R may be C₁₋₄ alkyl.

In one embodiment the imidazolidinone includes 1-(2-amino-ethyl)-imidazolidin-2-one (may also be called aminoethylethyleneurea), 1-(3-amino-propyl)-imidazolidin-2-one, 1-(2-hydroxy-ethyl)-imidazolidin-2-one, 1-(3-amino-propyl)-pyrrolidin-2-one, 1-(3-amino-ethyl-pyrrolidin-2-one, or mixtures thereof.

In one embodiment the copolymer may be reacted with an amine-containing compound selected from morpholines, imidazolidinones, and mixtures thereof.

Other illustrative copolymers and interpolymers useful as viscosity modifiers of this disclosure are described, for example, in U.S. Patent Application Publication Nos. 2010/0144566 and 2011/0190182, and also WO 2011/066242, the disclosures of which are incorporated herein in their entirety.

Alkylated Aromatic Co-Base Stock Components

Alkylated aromatic base stock components useful in this disclosure include, for example, alkylated naphthalenes and alkylated benzenes. The alkylated aromatic base stock can be any hydrocarbyl molecule that contains at least 5% of its weight derived from an aromatic moiety such as a benzenoid moiety or naphthenoid moiety, or their derivatives. These alkylated aromatic base stocks include alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, alkylated thiodiphenol, and the like. The alkylated aromatic base stock can be mono-alkylated, dialkylated, polyalkylated, and the like. The aromatic can be mono- or poly-functionalized. The hydrocarbyl groups can range from C₆ up to C₆₀ with a range of C₈ to C₄₀ often being preferred. A mixture of hydrocarbyl groups is often preferred. The hydrocarbyl group can optionally contain sulfur, oxygen, and/or nitrogen containing substituents. The aromatic group can also be derived from natural (petroleum) sources, provided at least 5% of the molecule is comprised of an above-type aromatic moiety. Viscosities at 100° C. of approximately 3 cSt to 50 cSt are preferred, with viscosities of approximately 3.4 cSt to 20 cSt often being more preferred for the alkylated aromatic base stock. Naphthalene or methyl naphthalene, for example, can be alkylated with olefins such as octene, decene, dodecene, tetradecene or higher, mixtures of similar olefins, and the like.

Illustrative alkylated naphthalenes useful in the present disclosure are described, for example, in U.S. Patent Publication No. 2008/0300157.

Examples of typical alkyl naphthalenes are mono-, di-, tri-, tetra-, or penta-C₃ alkyl naphthalene. C₄ alkyl naphthalene, C₅ alkylnaphthalene, C₆ alkyl naphthalene, C₈ alkyl naphthalene, C₁₀ alkyl naphthalene, C₁₋₂ alkyl naphthalene, C₁₋₄ alkyl naphthalene, C₁₋₆ alkyl naphthalene, C₁₋₈ alkyl naphthalene, etc., C₁₀-C₁₄ mixed alkyl naphthalene, C₆-C₁₈ mixed alkyl naphthalene, or the mono-, di-, tri-, tetra-, or penta C₃, C₄, C₅, C₆, C₈, C₁₀, C₁₂, C₁₄, C₁₆, C₁₈ or mixture thereof alkyl monomethyl, dimethyl, ethyl, diethyl, or methylethyl naphthalene, or mixtures thereof. The alkyl group can also be branched alkyl group with C₁₀ to C₃₀₀, e.g., C₂₄-C₅₆ branched alkyl naphthalene, C₂₄-C₅₆ branched alkyl mono-, di-, tri-, tetra- or penta-C₁-C₄ naphthalene. These branched alkyl group substituted naphthalenes or branched alkyl group substituted mono-, tri-, tetra- or penta C₁-C₄ naphthalene can also be used as mixtures with the previously recited materials. These branched alkyl group can be prepared from oligomerization of small olefins, such as C₅ to C₂₄ alpha- or internal-olefins. When the branched alkyl group is very large (that is 8 to 300 carbons), usually only one or two of such alkyl groups are attached to the naphthalene core. The alkyl groups on the naphthalene ring can also be mixtures of the above alkyl groups. Sometimes mixed alkyl groups are advantageous because they provide more improvement of pour points and low temperature fluid properties. The fully hydrogenated fluid alkylnaphthalenes can also be used for blending with GTL base stock/base oil, but the alkyl naphthalenes are preferred.

Typically the alkyl naphthalenes are prepared by alkylation of naphthalene or short chain alkyl naphthalene, such as methyl or di-methyl naphthalene, with olefins, alcohols or alkylchlorides of 6 to 24 carbons over acidic catalyst inducing typical Friedel-Crafts catalysts. Typical Friedel-Crafts catalysts are AlCl₃, BF₃, HT, zeolites, amorphous alumniosilicates, acid clays, acidic metal oxides or metal salts, USY, etc.

Methods for the production of alkylnaphthalenes suitable for use in the present disclosure are described in U.S. Pat. Nos. 5,034,563, 5,516,954, and 6,436,882, as well as in references cited in those patents as well as taught elsewhere in the literature. Because alkylated naphthalene synthesis techniques are well known to those skilled in the art as well as being well documented in the literature such techniques will not be further addressed herein.

The naphthalene or mono- or di-substituted short chain alkyl naphthalenes can be derived from any conventional naphthalene-producing process from petroleum, petrochemical process or coal process or source stream. Naphthalene-containing feeds can be made from aromatization of suitable streams available from the F-T process. For example, aromatization of olefins or paraffins can produce naphthalene or naphthalene-containing component. Many medium or light cycle oils from petroleum refining processes contain significant amounts of naphthalene, substituted naphthalenes or naphthalene derivatives. Indeed, substituted naphthalenes recovered from whatever source, if possessing up to three alkyl carbons can be used as raw material to produce alkylnaphthalene for this disclosure. Furthermore, alkylated naphthalenes recovered from whatever source or processing can be used in the present method, provided they possess kinematic viscosities, VI, pour point, etc.

Suitable alkylated naphthalenes are available commercially from ExxonMobil under the tradename Synesstic AN or from King Industries under the tradename NA-Lube naphthalene-containing fluids.

Illustrative alkylated benzenes useful in this disclosure include, for example, those described in U.S. Patent Publication 2008/0300157. Alkylated benzenes having a viscosity at 100° C. of 1.5 to 600 cS, VI of 0 to 200 and pour point of 0° C. or less, preferably −15° C. or less, more preferably −25° C. or less, still more preferably −35° C. or less, most preferably −60° C. or less are useful for this disclosure.

Illustrative monoalkylated benzenes include, for example, linear C₁₀ to C₃₀ alkyl benzene or a C₁₀-C₃₀₀ branched alkyl benzene, preferably C₁₀-C₁₀₀ branched alkyl benene, more preferably C₁₅-C₅₀ branched alkyl group. Illustrative miltialkylated benzenes include, fir example, those in which one or two of the alkyl groups can be small alkyl radical of C₁ to C₅ alkyl group, preferably C₁-C₂ alkyl group. The other alkyl group or groups can be any combination of linear C₁₀-C₃₀ alkyl group, or branched C₁₀ and higher up to C₃₀₀ alkyl group, preferably C₁₅C₅₀ branched alkyl group. These branched large alkyl radicals can be prepared from the oligomerization or polymerization of C₃ to C₂₀, internal or alpha-olefins or mixture of these olefins. The total number of carbons in the alkyl substituents ranged from C₁₀ to C₃₀₀. Preferred alkyl benzene fluids can be prepared according to U.S. Pat. Nos. 6,071,864 and 6,491,809.

Included in this class of base stock blend components are, for example, long chain alkylbenzenes and long chain alkyl naphthalenes which are preferred materials since they are hydrolytically stable and may therefore be used in combination with the PAO component of the base stock in wet applications. The alkylnaphthalenes are known materials and are described, for example, in U.S. Pat. No. 4,714,794. The use of a mixture of monoalkylated and polyalkylated naphthalene as a base for synthetic functional fluids is also described in U.S. Pat. No. 4,604,491. The preferred alkylnaphthalenes are those having a relatively long chain alkyl group typically from 10 to 40 carbon atoms although longer chains may be used if desired, Alkylnaphthalenes produced by alkylating naphthalene with an olefin of 14 to 20 carbon atoms has particularly good properties, especially when zeolites such as the large pore size zeolites are used as the alkylating catalyst, as described in U.S. Pat. No. 5,602,086. These alkylnaphthalenes are predominantly monosubstituted naphthalenes with attachment of the alkyl group taking place predominantly at the 1- or 2-position of the alkyl chain. The presence of the long chain alkyl groups confers good viscometric properties on the alkyl naphthalenes, especially when used in combination with the PAO components which are themselves materials of high viscosity index, low pour point and good fluidity.

An alternative secondary blending stock is an alkylbenzene or mixture of alkylbenzenes. The alkyl substituents in these fluids are typically alkyl groups of 8 to 25 carbon atoms, usually from 10 to 18 carbon atoms and up to three such substituents may be present, as described in ACS Petroleum Chemistry Preprint 1053-1058, “Poly n-Alkylbenzene Compounds: A Class of Thermally Stable and Wide Liquid Range Fluids”, Eapen et al, Phila. 1984. Tri-alkyl benzenes may also be produced by the cydodimerization of 1-alkynes of 8 to 12 carbon atoms as described in U.S. Pat. No. 5,055,626. Other alkylbenzenes are described in U.S. Pat. No. 4,658,072. Alkylbenzenes have been used as lubricant base stocks, especially for low temperature applications. They are commercially available from producers of linear alkylbenzenes (LABs) such as Vista Chemical Co, Huntsman Chemical Co. as well as ChevronTexaco and Nippon Oil Co. The linear alkylbenzenes typically have good low pour points and low temperature viscosities and VI values greater than 100 together with good solvency for additives. Other alkylated aromatics which may be used when desirable are described, for example, in “Synthetic Lubricants and High Performance Functional Fluids”, Dressler, H., chap 5, (R. L. Shubkin (Ed.)), Marcel Dekker, N.Y. 1993.

Also included in this class and with very desirable lubricating characteristics are the alkylated aromatic compounds including the alkylated diphenyl compounds such as the alkylated diphenyl oxides, alkylated diphenyl sulfides and alkylated diphenyl methanes and the alkylated phenoxathins as well as the alkylthiophenes, alkyl benzofurans and the ethers of sulfur-containing aromatics, Lubricant blend components of this type are described, for example, in U.S. Pat. Nos. 5,552,071; 5,171,195; 5,395,538; 5,344,578; and 5,371,248.

The alkylated aromatic base stock component is typically used in an amount from 1% to 15%, preferably 2% to 10%, and more preferably 4% to 8%, depending on the application.

The alkylated aromatic base stock component is preferably present in an amount sufficient for the lubricating oil to pass ASTM Sequence IV A wear test (D6891) and/or ASTM Sequence IIIG wear test (7320). Also, the alkylated aromatic base stock component is preferably present in an amount sufficient for the lubricating oil to pass ASTM D6594 corrosion test and/or D130 corrosion test.

Other Additives

The formulated lubricating oil useful in the present disclosure may additionally contain one or more of the other commonly used lubricating oil performance additives including but not limited to dispersants, other detergents, corrosion inhibitors, rust inhibitors, metal deactivators, other antiwear agents and/or extreme pressure additives, anti-seizure agents, wax modifiers, viscosity index improvers, fluid-loss additives, seal compatibility agents, other friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others. For a review of many commonly used additives, see Klamann in Lubricants and Related Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0. Reference is also made to “Lubricant Additives” by M. W. Ranney, published by Noyes Data Corporation of Parkridge, N.J. (1973).

The types and quantities of performance additives used in combination with the instant disclosure in lubricant compositions are not limited by the examples shown herein as illustrations.

Antioxidants

Typical antioxidant include phenolic antioxidants, aminic antioxidants and oil-soluble copper complexes.

The phenolic antioxidants include sulfurized and non-sulfurized phenolic antioxidants. The terms “phenolic type” or “phenolic antioxidant” used herein includes compounds having one or more than one hydroxyl group bound to an aromatic ring which may itself be mononuclear, e.g., benzyl, or poly-nuclear, e.g., naphthyl and Spiro aromatic compounds. Thus “phenol type” includes phenol per se, catechol, resorcinol, hydroquinone, naphthol, etc., as well as alkyl or alkenyl and sulfurized alkyl or alkenyl derivatives thereof, and bisphenol type compounds including such bi-phenol compounds linked by alkylene bridges sulfuric bridges or oxygen bridges. Alkyl phenols include mono- and poly-alkyl or alkenyl phenols, the alkyl or alkenyl group containing from 3-100 carbons, preferably 4 to 50 carbons and sulfurized derivatives thereof, the number of alkyl or alkenyl groups present in the aromatic ring ranging from 1 to up to the available unsatisfied valences of the aromatic ring remaining after counting the number of hydroxyl groups bound to the aromatic ring.

Generally, therefore, the phenolic anti-oxidant may be represented by the general formula:

(R)_(x)—Ar—(OH)_(y)

where Ar is selected from the group consisting of:

wherein R is a C₃-C₁₀₀ alkyl or alkenyl group, a sulfur substituted alkyl or alkenyl group, preferably a C₄-C₅₀ alkyl or alkenyl group or sulfur substituted alkyl or alkenyl group, more preferably C₃-C₁₀₀ alkyl or sulfur substituted alkyl group, most preferably a C₄-C₅₀ alkyl group, R^(g) is a C₁-C₁₀₀ alkylene or sulfur substituted alkylene group, preferably a C₂-C₅₀ alkylene or sulfur substituted alkylene group, more preferably a C₂-C₂ alkylene or sulfur substituted alkylene group, y is at least 1 to up to the available valences of Ar, x ranges from 0 to up to the available valances of Ar-y, z ranges from 1 to 10, n ranges from 0 to 20, and m is 0 to 4 and p is 0 or 1, preferably y ranges from 1 to 3, x ranges from 0 to 3, z ranges from 1 to 4 and n ranges from 0 to 5, and p is 0.

Preferred phenolic anti-oxidant compounds are the hindered phenolics and phenolic esters which contain a sterically hindered hydroxyl group, and these include those derivatives of dihydroxy aryl compounds in which the hydroxyl groups are in the o- or p-position to each other. Typical phenolic anti-oxidants include the hindered phenols substituted with C₁+ alkyl groups and the alkylene coupled derivatives of these hindered phenols. Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl phenol; 2-methyl-6-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4 methyl phenol; 2,6-di-t-butyl-4-ethyl phenol; and 2,6-di-t-butyl 4 alkoxy phenol; and

Phenolic type antioxidants are well known in the lubricating industry and commercial examples such as Ethanox® 1710, Irganox® 1076, Irganox® L1035, Irganox® 1010, Irganox® L109, Irganox® L118, Irganox® L135 and the like are familiar to those skilled in the art. The above is presented only by way of exemplification, not limitation on the type of phenolic anti-oxidants which can be used.

The phenolic antioxidant can be employed in an amount in the range of 0.1 to 3 wt %, preferably 0.25 to 2.5 wt %, more preferably 0.5 to 2 wt % on an active ingredient basis.

Aromatic amine antioxidants include phenyl-α-naphthyl amine which is described by the following molecular structure:

wherein R^(z) is hydrogen or a C₁ to C₁₄ linear or C₃ to C₁₄ branched alkyl group, preferably C₁ to C₁₀ linear or C₃ to C₁₀ branched alkyl group, more preferably linear or branched C₆ to C₈ and n is an integer ranging from 1 to 5 preferably 1. A particular example is Irganox L06.

Other aromatic amine antioxidants include other alkylated and non-alkylated aromatic amines such as aromatic monoamines of the formula R⁸R⁹R¹⁰N where R⁸ is an aliphatic, aromatic or substituted aromatic group, R⁹ is an aromatic or a substituted aromatic group, and R¹⁰ is H, alkyl, aryl or R¹¹S(O)_(x)R¹² where R¹¹ is an alkylene, alkenylene, or aralkylene group, R¹² is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1 or 2. The aliphatic group R⁸ may contain from 1 to 20 carbon atoms, and preferably contains from 6 to 12 carbon atoms. The aliphatic group is a saturated aliphatic group. Preferably, both R⁸ and R⁹ are aromatic or substituted aromatic groups, and the aromatic group may be a fused ring aromatic group such as naphthyl. Aromatic groups R⁸ and R⁹ may be joined together with other groups such as S.

Typical aromatic amines anti-oxidants have alkyl substituent groups of at least 6 carbon atoms. Examples of aliphatic groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups will not contain more than 14 carbon atoms. The general types of such other additional amine antioxidants which may be present include diphenylamines, phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of two or more of such other additional aromatic amines may also be present. Polymeric amine antioxidants can also be used.

Another class of antioxidant used in lubricating oil compositions and which may also be present are oil-soluble copper compounds. Any oil-soluble suitable copper compound may be blended into the lubricating oil. Examples of suitable copper antioxidants include copper dihydrocarbyl thio- or dithio-phosphates and copper salts of carboxylic acid (naturally occurring or synthetic). Other suitable copper salts include copper dithiacarbamates, sulphonates, phenates, and acetylacetonates. Basic, neutral, or acidic copper Cu(I) and or Cu(II) salts derived from alkenyl succinic acids or anhydrides are known to be particularly useful.

Such antioxidants may be used individually or as mixtures of one or more types of antioxidants, the total amount employed being an amount of 0.50 to 5 wt %, preferably 0.75 to 3 wt % (on an as-received basis).

Detergents

Illustrative detergents useful in this disclosure include, for example, alkali metal detergents, alkaline earth metal detergents, or mixtures of one or more alkali metal detergents and one or more alkaline earth metal detergents, A typical detergent is an anionic material that contains a long chain hydrophobic portion of the molecule and a smaller anionic or oleophobic hydrophilic portion of the molecule. The anionic portion of the detergent is typically derived from an organic acid such as a sulfur acid, carboxylic acid, phosphorous acid, phenol, or mixtures thereof. The counterion is typically an alkaline earth or alkali metal.

Salts that contain a substantially stochiometric amount of the metal are described as neutral salts and have a total base number (TBN, as measured by ASTM D2896) of from 0 to 80. Many compositions are overbased, containing large amounts of a metal base that is achieved by reacting an excess of a metal compound (a metal hydroxide or oxide, for example) with an acidic gas (such as carbon dioxide). Useful detergents can be neutral, mildly overbased, or highly overbased.

Alkaline earth phenates are another useful class of detergent. These detergents can be made by reacting alkaline earth metal hydroxide or oxide (CaO, Ca(OH)₂, BaO, Ba(OH)₂, MgO, Mg(OH)₂, for example) with an alkyl phenol or sulfurized alkylphenol. Useful alkyl groups include straight chain or branched C₁-C₃₀ alkyl groups, preferably, C₄-C₂₀ or mixtures thereof. Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It should be noted that starting alkylphenols may contain more than one alkyl substituent that are each independently straight chain or branched and can be used from 0.5 to 6 weight percent. When a non-sulfurized alkylphenol is used, the sulfurized product may be obtained by methods well known in the art. These methods include heating a mixture of alkylphenol and sulfurizing agent (including elemental sulfur, sulfur halides such as sulfur dichloride, and the like) and then reacting the sulfurized phenol with an alkaline earth metal base.

Metal salts of carboxylic acids are also useful as detergents. These carboxylic acid detergents may be prepared by reacting a basic metal compound with at least one carboxylic acid and removing free water from the reaction product. These compounds may be overbased to produce the desired TBN level. Detergents made from salicylic acid are one preferred class of detergents derived from carboxylic acids, Useful salicylates include long chain alkyl salicylates. One useful family of compositions is of the formula

where R is an alkyl group having 1 to 30 carbon atoms, n is an integer from 1 to 4, and M is an alkaline earth metal. Preferred R groups are alkyl chains of at least C₁₁, preferably C₁₃ or greater. R may be optionally substituted with substituents that do not interfere with the detergent's function. M is preferably, calcium, magnesium, or barium. More preferably, M is calcium.

Hydrocarbyl-substituted salicylic acids may be prepared from phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The metal salts of the hydrocarbyl-substituted salicylic acids may be prepared by double decomposition of a metal salt in a polar solvent such as water or alcohol.

Alkaline earth metal phosphates are also used as detergents and are known in the art.

Detergents may be simple detergents or what is known as hybrid or complex detergents. The latter detergents can provide the properties of two detergents without the need to blend separate materials. See U.S. Pat. No. 6,034,039.

Preferred detergents include calcium phenates, calcium sulfonates, calcium salicylates, magnesium phenates, magnesium sulfonates, magnesium salicylates and other related components (including borated detergents), and mixtures thereof. Preferred detergents include magnesium sulfonate and calcium salicylate.

The detergent concentration in the lubricating oils of this disclosure can range from 1.0 to 6.0 weight percent, preferably 2.0 to 5.0 weight percent, and more preferably from 2.0 weight percent to 4.0 weight percent, based on the total weight of the lubricating oil.

As used herein, the detergent concentrations are given on an “as delivered” basis. Typically, the active detergent is delivered with a process oil. The “as delivered” detergent typically contains from 20 weight percent to 80 weight percent, or from 40 weight percent to 60 weight percent, of active detergent in the “as delivered” detergent product.

Dispersants

During engine operation, oil-insoluble oxidation byproducts are produced. Dispersants help keep these byproducts in solution, thus diminishing their deposition on metal surfaces. Dispersants may be ashless or ash-forming in nature. Preferably, the dispersant is ashless. So called ashless dispersants are organic materials that form substantially no ash upon combustion. For example, non-metal-containing or borated metal-free dispersants are considered ashless. In contrast, metal-containing detergents discussed above form ash upon combustion.

Suitable dispersants typically contain a polar group attached to a relatively high molecular weight hydrocarbon chain. The polar group typically contains at least one element of nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

A particularly useful class of dispersants are the alkenylsuccinic derivatives, typically produced by the reaction of a long chain substituted alkenyl succinic compound, usually a substituted succinic anhydride, with a polyhydroxy or polyamino compound. The long chain group constituting the oleophilic portion of the molecule which confers solubility in the oil, is normally a polyisobutylene group. Many examples of this type of dispersant are well known commercially and in the literature. Exemplary U.S. patents describing such dispersants are U.S. Pat. Nos. 3,172,892; 3,215,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersant are described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. A further description of dispersants may be found, for example, in European Patent Application No. 471 071, to which reference is made for this purpose.

Hydrocarbyl-substituted succinic acid compounds are popular dispersants. In particular, succinimide, succinate esters, or succinate ester amides prepared by the reaction of a hydrocarbon-substituted succinic acid compound preferably having at least 50 carbon atoms in the hydrocarbon substituent, with at least one equivalent of an alkylene amine are particularly useful.

Succinimides are formed by the condensation reaction between alkenyl succinic anhydrides and amines. Molar ratios can vary depending on the amine or polyamine. For example, the molar ratio of alkenyl succinic anhydride to TEPA can vary from 1:1 to 5:1.

Succinate esters are formed by the condensation reaction between alkenyl succinic anhydrides and alcohols or polyols. Molar ratios can vary depending on the alcohol or polyol used. For example, the condensation product of an alkenyl succinic anhydride and pentaerythritol is a useful dispersant.

Succinate ester amides are formed by condensation reaction between alkenyl succinic anhydrides and alkanol amines. For example, suitable alkanol amines include ethoxylated polyalkylpolyamines, propoxylated polyalkylpolyamines and polyalkenylpolyamines such as polyethylene polyamines. One example is propoxylated hexamethylenediamine.

The molecular weight of the alkenyl succinic anhydrides will typically range between 800 and 2,500. The above products can be post-reacted with various reagents such as sulfur, oxygen, formaldehyde, carboxylic acids such as oleic acid, and boron compounds such as borate esters or highly borated dispersants. The dispersants can be borated with from 0.1 to 5 moles of boron per mole of dispersant reaction product.

Mannich base dispersants are made from the reaction of alkylphenols, formaldehyde, and amines. Process aids and catalysts, such as oleic acid and sulfonic acids, can also be part of the reaction mixture. Molecular weights of the alkylphenols range from 800 to 2,500 or more.

Typical high molecular weight aliphatic acid modified Mannich condensation products can be prepared from high molecular weight alkyl-substituted hydroxyaromatics or HN(R)₂ group-containing reactants.

Examples of high molecular weight alkyl-substituted hydroxyaromatic compounds are polypropylphenol, polybutylphenol, and other polyalkylphenols. These polyalkylphenols can be obtained by the alkylation, in the presence of an alkylating catalyst, such as BF₃, of phenol with high molecular weight polypropylene, polybutylene, and other polyalkylene compounds to give alkyl substituents on the benzene ring of phenol having an average 600-100,000 molecular weight.

Examples of HN(R)₂ group-containing reactants are alkylene polyamines, principally polyethylene polyamines. Other representative organic compounds containing at least one HN(R)₂ group suitable for use in the preparation of Mannich condensation products are well known and include the mono- and di-amino alkanes and their substituted analogs, e.g., ethylamine and diethanol amine; aromatic diamines, e.g., phenylene diamine, diamino naphthalenes; heterocyclic amines, e.g., morpholine, pyrrole, pyrrolidine, imidazole, imidazolidine, and piperidine; melamine and their substituted analogs.

Examples of alkylene polyamine reactants include ethylenediamine, diethylene triamine, triethylene tetraamine, tetraethylene pentaamine, pentaethylene hexamine, hexaethylene heptaamine, heptaethylene octaamine, octaethylene nonaamine, nonaethylene decamine, and decaethylene undecamine and mixture of such amines having nitrogen contents corresponding to the alkylene polyamines, in the formula H₂N—(Z—NH—)_(n)H, mentioned before, Z is a divalent ethylene and n is 1 to 10 of the foregoing formula. Corresponding propylene polyamines such as propylene diamine and di-, tri-, tetra-, pentapropylene tri-, tetra-, penta- and hexaamines are also suitable reactants. The alkylene polyamines are usually obtained by the reaction of ammonia and dihalo alkanes, such as dichloro alkanes. Thus the alkylene polyamines obtained from the reaction of 2 to 11 moles of ammonia with 1 to 10 moles of dichloroalkanes having 2 to 6 carbon atoms and the chlorines on different carbons are suitable alkylene polyamine reactants.

Aldehyde reactants useful in the preparation of the high molecular products useful in this disclosure include the aliphatic aldehydes such as formaldehyde (also as paraformaldehyde and formalin), acetaldehyde and aldol (β-hydroxybutyraldehyde). Formaldehyde or a formaldehyde-yielding reactant is preferred.

Preferred dispersants include borated and non-borated succinimides, including those derivatives from mono-succinimides, bis-succinimides, and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbyl succinimide is derived from a hydrocarbylene group such as polyisobutylene having a Mn of from 500 to 5000 or more or a mixture of such hydrocarbylene groups. Other preferred dispersants include succinic acid-esters and amides, alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives, and other related components. Such additives may be used in an amount of 0.1 to 20 wt %, preferably 0.1 to 8 wt %, more preferably 1 to 6 wt % (on an as-received basis) based on the weight of the total lubricant.

Pour Point Depressants

Conventional pour point depressants (also known as lube oil flow improvers) may also be present. Pour point depressant may be added to lower the minimum temperature at which the fluid will flow or can be poured. Examples of suitable pour point depressants include alkylated naphthalenes polymethacrylates, polyacrylates, polyarylamides, condensation products of haloparaffin waxes and aromatic compounds, vinyl carboxylate polymers, and terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers. Such additives may be used in amount of 0.0 to 0.5 wt %, preferably 0 to 0.3 wt %, more preferably 0.001 to 0.1 wt % on an as-received basis.

Corrosion Inhibitors/Metal Deactivators

Corrosion inhibitors are used to reduce the degradation of metallic parts that are in contact with the lubricating oil composition. Suitable corrosion inhibitors include aryl thiazines, alkyl substituted dimercapto thiodiazoles thiadiazoles and mixtures thereof. Such additives may be used in an amount of 0.01 to 5 wt %, preferably 0.01 to 1.5 wt %, more preferably 0.01 to 0.2 wt %, still more preferably 0.01 to 0.1 wt % (on an as-received basis) based on the total weight of the lubricating oil composition.

Seal Compatibility Additives

Seal compatibility agents help to swell elastomeric seals by causing a chemical reaction in the fluid or physical change in the elastomer. Suitable seal compatibility agents for lubricating oils include organic phosphates, aromatic esters, aromatic hydrocarbons, esters (butylbenzyl phthalate, for example), and polybutenyl succinic anhydride and sulfolane-type seal swell agents such as Lubrizol 730-type seal swell additives. Such additives may be used in an amount of 0.01 to 3 wt %, preferably 0.01 to 2 wt % on an as-received basis.

Antifoam Agents

Antifoam agents may advantageously be added to lubricant compositions. These agents retard the formation of stable foams. Silicones and organic polymers are typical antifoam agents. For example, polysiloxanes, such as silicon oil or polydimethyl siloxane, provide antifoam properties. Antifoam agents are commercially available and may be used in conventional minor amounts along with other additives such as demulsifiers; usually the amount of these additives combined is less than 1 percent, preferably 0.001 to 0.5 wt %, more preferably 0.001 to 0.2 wt %, still more preferably 0.0001 to 0.15 wt % (on an as-received basis) based on the total weight of the lubricating oil composition.

Inhibitors and Antirust Additives

Antirust additives (or corrosion inhibitors) are additives that protect lubricated metal surfaces against chemical attack by water or other contaminants. One type of antirust additive is a polar compound that wets the metal surface preferentially, protecting it with a film of oil. Another type of antirust additive absorbs water by incorporating it in a water-in-oil emulsion so that only the oil touches the surface. Yet another type of antirust additive chemically adheres to the metal to produce a non-reactive surface. Examples of suitable additives include zinc dithiophosphates, metal phenolates, basic metal sulfonates, fatty acids and amines. Such additives may be used in an amount of 0.01 to 5 wt %, preferably 0.01 to 1.5 wt % on an as-received basis.

The term “organo molybdenum-nitrogen complexes” embraces the organo molybdenum-nitrogen complexes described in U.S. Pat. No. 4,889,647. The complexes are reaction products of a fatty oil, dithanolamine and a molybdenum source. Specific chemical structures have not been assigned to the complexes. U.S. Pat. No. 4,889,647 reports an infrared spectrum for a typical reaction product of that disclosure; the spectrum identifies an ester carbonyl band at 1740 cm⁻¹ and an amide carbonyl band at 1620 cm⁻¹. The fatty oils are glyceryl esters of higher fatty acids containing at least 12 carbon atoms up to 22 carbon atoms or more. The molybdenum source is an oxygen containing compound such as ammonium molybdates, molybdenum oxides and mixtures.

Other organo molybdenum complexes which can be used in the present disclosure are tri-nuclear molybdenum-sulfur compounds described in EP 1 040 115 and WO 99/31113 and the molybdenum complexes described in U.S. Pat. No. 4,978,464.

Viscosity Modifiers

In addition to the copolymers described herein as part of the disclosure the lubricating composition may optionally further contain other known viscosity modifiers. The viscosity modifiers may be hydrogenated styrene-butadiene rubbers, ethylene-propylene copolymers, hydrogenated styrene-isoprene polymers, hydrogenated dime polymers, polyalkyl styrenes, polyolefins, esters of maleic anhydride-styrene copolymers, or mixtures thereof.

Antiwear Agents

The lubricating compositions can include at least one antiwear agent. Examples of suitable antiwear agents include oil soluble amine salts of phosphorus compounds, sulphurized olefins, metal dihydrocarbyldithio-phosphates (such as zinc dialkyldithiophosphates), thiocarbamate-containing compounds, such as thiocarbamate esters, thiocarbamate amides, thiocarbamic ethers, alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamyl) disulphides.

In one embodiment the oil soluble phosphorus amine sail antiwear agent includes an amine salt of a phosphorus acid ester or mixtures thereof. The amine salt of a phosphorus acid ester includes phosphoric acid esters and amine sails thereof; dialkyldithiophosphoric acid esters and amine salts thereof; amine salts of phosphites; and amine salts of phosphorus-containing carboxylic esters, ethers, and amides; and mixtures thereof. The amine salt of a phosphorus acid ester may be used alone or in combination.

In one embodiment the oil soluble phosphorus amine salt includes partial amine salt-partial metal salt compounds or mixtures thereof. In one embodiment the phosphorus compound further includes a sulphur atom in the molecule. In one embodiment the amine salt of the phosphorus compound may be ashless, i.e., metal-free (prior to being mixed with other components.

The amines which may be suitable for use as the amine salt include primary amines, secondary amines, tertiary amines, and mixtures thereof. The amines include those with at least one hydrocarbyl group, or, in certain embodiments, two or three hydrocarbyl groups. The hydrocarbyl groups may contain 2 to 30 carbon atoms, or in other embodiments 8 to 26, or 10 to 20, or 13 to 19 carbon atoms.

Primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine, and dodecylamine, as well as such fatty amines as n-octylamine, n-decylamine, n-dodeclyamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine and oleyamine. Other useful fatty amines include commercially available fatty amines such as “Armeen®” amines (products available from Akzo Chemicals, Chicago, Ill.), such as Armeen C, Armeen O, Armeen OL, Armeen T, Armeen HT, Armeen S and Armeen SD, wherein the letter designation relates to the fatty group, such as coco, oleyl, tallow, or stearyl groups.

Examples of suitable secondary amines include dim ethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine and ethylamylamine. The secondary amines may be cyclic amines such as piperidine, piperazine and morpholine.

The amine may also be a tertiary-aliphatic primary amine. The aliphatic group in this case may be an alkyl group containing 2 to 30, or 6 to 26, or 8 to 24 carbon atoms. Tertiary alkyl amines include monoamines such as tert-butylamine, tert-hexylamine, 1-methyl-1-amino-cyclohexane, tert-octylamine, tert-decylamine, tertdodecylamine, tert-tetradecylamine, tert-hexadecylamine, tert-octadecylamine, tert-tetracosanylamine, and tert-octacosanylamine.

In one embodiment the phosphorus acid amine salt includes an amine with C₁₁ to C₁₄ tertiary alkyl primary groups or mixtures thereof. In one embodiment the phosphorus acid amine salt includes an amine with C₁₄ to C₁₈ tertiary alkyl primary amines or mixtures thereof. In one embodiment the phosphorus acid amine salt includes an amine with C₁₈ to C₂₂ tertiary alkyl primary amines or mixtures thereof.

Mixtures of amities may also be used in the disclosure. In one embodiment a useful mixture of amines is “Primene® 81R” and “Primene® JMT.” Primene® 81R and Primene® JMT (both produced and sold by Rohm & Haas) are mixtures of C₁₁ to C₁₄ tertiary alkyl primary amines and C₁₈ to C₂₂ tertiary alkyl primary amines respectively.

In one embodiment oil soluble amine salts of phosphorus compounds include a sulphur-free amine salt of a phosphorus-containing compound may be obtained/obtainable by a process comprising: reacting an amine with either (i) a hydroxy-substituted di-ester of phosphoric acid, or (ii) a phosphorylated hydroxy-substituted di- or tri-ester of phosphoric acid. A more detailed description of compounds of this type is disclosed in International Application PCT/US08/051126.

In one embodiment the hydrocarbyl amine salt of an alkylphosphoric acid ester is the reaction product of a C₁₄ to C_(is) alkylated phosphoric acid with Primene 81RT™ (produced and sold by Rohm & Haas) which is a mixture of C₁₁ to C₁₄ tertiary alkyl primary amines.

Examples of hydrocarbyl amine salts of dialkyldithiophosphoric acid esters include the reaction product(s) of isopropyl, methyl-amyl (4-methyl-2-pentyl or mixtures thereof), 2-ethylhexyl, heptyl, octyl or nonyl dithiophosphoric acids with ethylene diamine, morpholine, or Primene 81R™, and mixtures thereof.

In one embodiment the dithiophosphoric acid may be reacted with an epoxide or a glycol. This reaction product is further reacted with a phosphorus acid, anhydride, or lower ester. The epoxide includes an aliphatic epoxide or a styrene oxide. Examples of useful epoxides include ethylene oxide, propylene oxide, butene oxide, octene oxide, dodecene oxide, and styrene oxide. In one embodiment the epoxide may be propylene oxide. The glycols may be aliphatic glycols having from 1 to 12, or from 2 to 6, or 2 to 3 carbon atoms. The dithiophosphoric acids, glycols, epoxides, inorganic phosphorus reagents and methods of reacting the same are described in U.S. Pat. Nos. 3,197,405 and 3,544,465. The resulting acids may then be salted with amines. An example of suitable dithiophosphoric acid is prepared by adding phosphorus pentoxide (64 grams) at 58° C. over a period of 45 minutes to 514 grams of hydroxypropyl 0,0-di(4-methyl-2-pentyl)phosphorodithioate (prepared by reacting di(4-methyl-2-pentyl)-phosphorodithioic acid with 1.3 moles of propylene oxide at 25° C.). The mixture may be heated at 75° C. for 2.5 hours, mixed with a diatomaceous earth and filtered at 70° C. The filtrate contains 1 1.8% by weight phosphorus, 15.2% by weight sulphur, and an acid number of 87 (bromophenol blue).

The dithiocarbamate-containing compounds may be prepared by reacting a dithiocarbamate acid or salt with an unsaturated compound. The dithiocarbamate containing compounds may also be prepared by simultaneously reacting an amine, carbon disulphide and an unsaturated compound. Generally, the reaction occurs at a temperature from 25° C. to 125° C.

Examples of suitable olefins that may be sulphurised to form an the sulphurised olefin include propylene, butylene, isobutylene, pentene, hexane, heptene, octane, nonene, decene, undecene, dodecene, undecyl, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixtures thereof. In one embodiment, hexadecene, heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixtures thereof and their dimers, trimers and tetramers are especially useful olefins. Alternatively, the olefin may be a Diels-Alder adduct of a diene such as 1,3-butadiene and an unsaturated ester, such as, butylacrylate.

Another class of sulphurised olefin includes fatty acids and their esters. The fatty acids are often obtained from vegetable oil or animal oil; and typically contain 4 to 22 carbon atoms. Examples of suitable fatty acids and their esters include triglycerides, oleic acid, linoleic acid, palmitoleic acid or mixtures thereof. Often, the fatty acids are obtained from lard oil, tall oil, peanut oil, soybean oil, cottonseed oil, sunflower seed oil or mixtures thereof. In one embodiment fatty acids and/or ester are mixed with olefins.

In an alternative embodiment, the ashless antiwear agent may be a monoester of a polyol and an aliphatic carboxylic acid, often an acid containing 12 to 24 carbon atoms. Often the monoester of a polyol and an aliphatic carboxylic acid is in the form of a mixture with a sunflower oil or the like, which may be present in the friction modifier mixture from 5 to 95, in several embodiments from 10 to 90, or from 20 to 85, or 20 to 80 weight percent of said mixture. The aliphatic carboxylic acids (especially a monocarboxylic acid) which form the esters are those acids typically containing 12 to 24, or from 14 to 20 carbon atoms. Examples of carboxylic acids include dodecanoic acid, stearic acid, lauric acid, behenic acid, and oleic acid.

Polyols include diols, triols, and alcohols with higher numbers of alcoholic OH groups. Polyhydric alcohols include ethylene glycols, including di-, tri- and tetraethylene glycols; propylene glycols, including di-, tri- and tetrapropylene glycols; glycerol; butane diol; hexane diol; sorbitol; arabitol; mannitol; sucrose; fructose; glucose; cyclohexane diol; erythritol; and penta-erythritols, including di- and tripentaerythritol. Often the polyol is diethylene glycol, triethylene glycol, glycerol, sorbitol, penta erythritol or dipentaerythritol.

The commercially available monoester known as “glycerol monooleate” is believed to include 60±5 percent by weight of the chemical species glycerol monooleate, along with 35±5 percent glycerol dioleate, and less than 5 percent trioleate and oleic acid. The amounts of the monoesters, described above, are calculated based on the actual, corrected, amount of polyol monoester present in any such mixture.

Extreme Pressure Agents

Extreme Pressure (EP) agents that are soluble in the oil include sulphur- and chlorosulphur-containing EP agents, chlorinated hydrocarbon EP agents and phosphorus EP agents. Examples of such EP agents include chlorinated wax; sulphurised olefins (such as sulphurised isobutylene), organic sulphides and polysulphides such as dibenzyldisulphide, bis-(chlorobenzyl)disulphide, dibutyl tetrasulphide, sulphurised methyl ester of oleic acid, sulphurised alkylphenol, sulphurised dipentene, sulphurised terpene, and sulphurised Diels-Alder adducts; phosphosulphurised hydrocarbons such as the reaction product of phosphorus sulphide with turpentine or methyl oleate; phosphorus esters such as the dihydrocarbon and trihydrocarbon phosphites, e.g., dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite; dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite and polypropylene substituted phenol phosphite; metal thiocarbamates such as zinc dioctyldithio carbamate and barium heptylphenol diacid; amine salts of alkyl and dialkylphosphoric acids or derivatives; and mixtures thereof (as described in U.S. Pat. No. 3,197,405).

Modifications, variations and the addition of other additive types to the lubricating compositions of this disclosure can include, for example, up to 1 weight percent of silicon or non-silicon based de-foamant, 1 weight percent or more of di-mercaptothiadiazole type copper passivator, and up to 8 weight percent of a friction modifier.

The method and lubricating compositions of this disclosure may be suitable for greases, gear oils, axle oils, drive shaft oils, traction oils, manual transmission oils, automatic transmission oils, metal working fluids, hydraulic oils, or internal combustion engine oils.

In one embodiment the method and lubricating composition of the disclosure may be suitable for at least one of gear oils, axle oils, drive shaft oils, traction oils, manual transmission oils or automatic transmission oils. In one embodiment the disclosure provides a method of lubricating a manual transmission.

An automatic transmission includes continuously variable transmissions (CVT), infinitely variable transmissions (IVT), toroidal transmissions, continuously slipping torque converter clutches (CSTCC), stepped automatic transmissions or dual clutch transmissions (DCT).

The internal combustion engines may be a 2-stroke or 4-stroke engines. Suitable internal combustion engines include marine diesel engines, aviation piston engines, low-load diesel engines, and automobile and truck engines.

As used herein, the term “(meth)acrylic” and related terms includes both acrylic and methacrylic groups.

As used herein, the term “a primary alcohol branched at the β- or higher position” relates to an alcohol with branching at the 2-position or a higher position (e.g., 3-, or 4-, or 5-, or 6-, or 7-position, etc.).

As used herein the number of carbon atoms present in the ester groups of the polymers of the disclosure is counted to include only those carbon atoms of the alcohol-derived portion of the ester group. Specifically, the number of carbon atoms excludes the carbonyl carbon of the ester.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include: hydrocarbon substituents, including aliphatic, alicyclic, and aromatic substituents; substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this disclosure, do not alter the predominantly hydrocarbon nature of the substituent; and hetero substituents, that is, substituents which similarly have a predominantly hydrocarbon character but contain other than carbon in a ring or chain.

In the above detailed description, the specific embodiments of this disclosure have been described in connection with its preferred embodiments. However, to the extent that the above description is specific to a particular embodiment or a particular use of this disclosure, this is intended to be illustrative only and merely provides a concise description of the exemplary embodiments. Accordingly, the disclosure is not limited to the specific embodiments described above, but rather, the disclosure includes all alternatives, modifications, and equivalents falling within the true scope of the appended claims. Various modifications and variations of this disclosure will be obvious to a worker skilled in the art and it is to be understood that such modifications and variations are to be included within the purview of this application and the spirit and scope of the claims.

The following examples are for purposes of illustration only and are non-limiting examples.

EXAMPLES

Lubricant compositions (i.e., gear oil blends) were prepared by blending a polyalphaolefin base stock (e.g., cPAO 4 and mPAO 150), a hybrid olefin ester polymer (HOEP) viscosity modifier, alkylated naphthalene (+2 wt %, +4 wt %, +6 wt % and +8 wt %) and a gear oil additive package. The HOEP viscosity modifier is available from Lubrizol Corporation and is also known as Meridian™ VL1207HX. The gear oil additive package is available from Lubrizol Corporation as Anglamol™ 2044.

Example 1

Shear stability was determined for lubricant compositions prepared as described hereinabove. The results in FIGS. 1, 2 and 3 show KRL shear stability of gear oils (as determined by CEC L-45-A-99) is improved when using an alkylated naphthalene in combination with the HOEP viscosity modifier, cPAO4 and mPAO 150. FIG. 1 graphically depicts KRL 20 hour shear test (as determined by CEC results for lubricating compositions shown in FIG. 2. FIG. 1 shows a reduction in % relative viscosity loss with incremental additions of alkylated naphthalene to the control gear oil.

FIG. 2 shows ingredients for control gear oil formulations with varying amounts of alkylated naphthalene and KRL 20 hour shear test (as determined by CEC L-45-A-99) results. The data shows that the addition of incremental amounts of alkylated naphyhalene result in lowering the percent (%) relative viscosity loss from 3.06% to 1.15%. Measured relative viscosity loss (in cSt) is lowered from 0.36 cSt to 0.13 cSt.

FIG. 3 shows ingredients for control gear oil formulations with varying amounts of alkylated naphthalene and KRL 20 hour shear test (as determined by CEC L-45-A-99) results. The data in FIG. 3 shows that viscosity loss (2.73%) peaks with use of 4 weight percent alkylated naphthalene, but then viscosity loss becomes significantly less at 8 weight percent alkylated naphthalene (1.99% loss). Another matched set of data shows that 8 weight percent alkylated naphthalene results in significantly less viscosity loss than use at 6 weight percent. Viscosity loss is 0.92% at 8 weight percent alkylated naphthalene versus 1.58% at 6 weight percent alkylated naphthalene. This unexpected benefit can continue with the use of 10 weight percent and 12 weight percent alkylated naphthalene. Other alkyl aromatics such as alkylated benzenes can also show similar improvements. Alkylated naphthalene can be monoalkylated, dialkylated, polyalkylated, or mixtures thereof. Monoalkylated alkylated naphthalenes are preferred.

All patents and patent applications, test procedures (such as ASTM methods, UL methods, and the like), and other documents cited herein are fully incorporated by reference to the extent such disclosure is not inconsistent with this disclosure and for all jurisdictions in which such incorporation is permitted.

When numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated. While the illustrative embodiments of the disclosure have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present disclosure, including all features which would be treated as equivalents thereof by those skilled in the art to which the disclosure pertains.

The present disclosure has been described above with reference to numerous embodiments and specific examples. Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious variations are within the full intended scope of the appended claims. 

What is claimed is:
 1. A lubricating composition having a kinematic viscosity (Kv₁₀₀) from 5 to 32.5 cSt at 100° C., and a viscosity index (VI) from 140 to 200; said lubricating composition comprising: a bi-modal blend lubricating oil comprising from 20 to 99 weight percent, based on the total weight of the bi-modal blend lubricating oil, of a low viscosity basestock having a Kv₁₀₀ from 2 to 8 cSt at 100° C., and from 1 to 20 weight percent, based on the total weight of the bi-modal blend lubricating oil, of a high viscosity basestock having a Kv₁₀₀ from 40 to 600 cSt at 100° C.; a viscosity modifier comprising a copolymer having units derived from monomers of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol; and an alkylated aromatic co-base stock in an amount form 1 to 12 weight percent, based on the total weight of the lubricating composition, and having a Kv₁₀₀ from 3 to 15 cSt at 100° C.; wherein shear stability (as determined by CEC L-45-A-99) is improved in a driveline device lubricated with said lubricating composition as compared to shear stability achieved using a lubricating composition containing no co-base stock or a co-base stock other than the alkylated aromatic co-base stock.
 2. The lubricating composition of claim 1 wherein the bi-modal blend lubricating oil comprises two or more Group I, II, III, IV, V and/or VI base oil stocks.
 3. The lubricating composition of claim 1 wherein the bi-modal blend lubricating oil comprises at least two synthetic polyalphaolefin (PAO) fluids, said PAO independently comprising a polymer of one or more C₈ to C₁₂ alphaolefin monomers.
 4. The lubricating composition of claim 1 having a kinematic viscosity (Kv₁₀₀) from 6 to 20 cSt at 100° C., and a VI from 150 to
 190. 5. The lubricating composition of claim 1 wherein the viscosity modifier is represented by the formula:

wherein Formula (I) comprises a copolymer backbone (BB), and one or more pendant groups, wherein BB is derived from a copolymer of (i) an α-olefin and (ii) ethylenically unsaturated carboxylic acid or derivatives thereof; X is a functional group which either (i) contains a carbon and at least one oxygen or nitrogen atom, or (ii) is an alkylene group with 1 to 5 carbon atoms, connecting the copolymer backbone and a branched hydrocarbyl group contained within ( )_(y); w is the number of pendant groups attached to the copolymer backbone, which is in the range of 2 to 2000; y is 0, 1, 2 or 3, provided that in at least 1 mol % of the pendant groups, y is not zero; and with the proviso that when y is 0, X is bonded to a terminal group in a manner sufficient to satisfy the valence of X, wherein the terminal group is selected from hydrogen, alkyl, aryl, a metal or ammonium cation, and mixtures thereof; p may be an integer in the range of 1 to 15; and R′ and R″ are independently linear or branched hydrocarbyl groups, and the combined total number of carbon atoms present in R′ and R″ is at least
 12. 6. The lubricating composition of claim 1 wherein the α-olefin is selected from the group consisting of 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, -pentadecene, 1-hexadecene, 1-hepta-decene 1-octadecene, and mixtures thereof; the ethylenically unsaturated carboxylic acid or derivative thereof is selected from the group consisting of acrylic acid, methyl acrylate, methacrylic acid, maleic acid or anhydride, fumaric acid, itaconic acid or anhydride or mixtures thereof, and substituted equivalents thereof; and the alcohol is selected from the group consisting of 2-ethylhexanol, 2-butyloctanol, 2-hexyldecanol, 2-octyldodecanol, 2-decyltetradecanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, eicosanol, and mixtures thereof.
 7. The lubricating composition of claim 1 wherein the viscosity modifier is a copolymer derived from monomers of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof, wherein 0.1 to 99.89 percent of the carboxylic acid units are esterified with a primary alcohol branched at the β- or higher position, wherein 0.1 to 99.89 percent of the carboxylic acid units are esterified with a linear alcohol or an alpha-branched alcohol, and wherein 0.01 to 10 percent of the carboxylic acid units has at least one of an amino-, amido- and/or imido-group.
 8. The lubricating composition of claim 1 wherein the alkylated aromatic co-base stock is selected from the group consisting of alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, and alkylated thiodiphenol.
 9. The lubricating composition of claim 1 wherein the alkylated aromatic co-base stock comprises an alkylated naphthalene or alkylated benzene.
 10. The lubricating composition of claim 1 wherein the alkylated aromatic co-base stock is mono-alkylated, dialkylated, or polyalkylated.
 11. The lubricating composition of claim 1 wherein the alkylated aromatic co-base stock is an alkyl naphthalene selected from the group consisting of mono-, di-, tri-, tetra-, or penta-C₃ alkyl naphthalene, C₄ alkyl naphthalene, C₅ alkylnaphthalene, C₆ alkyl naphthalene, C₈ alkyl naphthalene, C₁₀ alkyl naphthalene, C₁₋₂ alkyl naphthalene, C₁₋₄ alkyl naphthalene, C₁₋₆ alkyl naphthalene, C₁₋₈ alkyl naphthalene, C₁₀-C₁₄ mixed alkyl naphthalene, C₆-C₁₈ mixed alkyl naphthalene, or mono-, di-, tri-, tetra-, or penta C₃, C₄, C₅, C₆, C₈, C₁₀, C₁₂, C₁₄, C₁₆, C₁₈ or mixture thereof, alkyl monomethyl, dimethyl, ethyl, diethyl, or methylethyl naphthalene, or mixtures thereof.
 12. The lubricating composition of claim 1 wherein the bi-modal blend lubricating oil is present in an amount of from 45 weight percent to 98 weight percent, the viscosity modifier is present in an amount of from 1 weight percent to 40 weight percent, and the alkylated aromatic co-base stock is present in an amount of from 4 weight percent to 12 weight percent, based on the total weight of the lubricating composition.
 13. A process for producing the lubricating composition of claim 1, said process comprising: providing a bi-modal blend lubricating oil comprising from 20 to 99 weight percent of a low viscosity basestock having a Kv₁₀₀ from 2 to 8 cSt 100° C., and from 1 to 20 weight percent of a high viscosity basestock having a Kv₁₀₀ from 40 to 600 cSt at 100° C.; providing a viscosity modifier comprising a copolymer having units derived from monomers of (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol; providing an alkylated aromatic co-base stock in an amount form 1 to 12 weight percent and having a Kv₁₀₀ from 3 to 15 cSt at 100° C.; and blending the bimodal blend lubricating oil, viscosity modifier and alkylated aromatic co-base stock in amounts sufficient to produce the lubricating composition.
 14. A lubricant comprising the lubricating composition of claim
 1. 15. The lubricant of claim 14 further comprising one or more of an antioxidant, detergent, dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, antiwear, extreme pressure agent, friction modifier, and anti-rust additive.
 16. A method of lubricating a mechanical device comprising supplying to the device a lubricating composition of claim 1, wherein the mechanical device comprises a driveline device.
 17. The method of claim 16 wherein the driveline device comprises gears or transmissions.
 18. The lubricant of claim 14 which comprises an axle fluid or manual transmission fluid (MTF).
 19. A method for improving fuel efficiency, while maintaining or improving shear stability in a driveline device lubricated with a lubricating oil, by using as the lubricating oil a lubricant of claim
 14. 20. The method of claim 19 wherein the lubricating composition comprises from 4 weight percent to 12 weight percent of the alkylated aromatic co-base stock, based on the total weight of the lubricating composition. 